Answer:
They will need 1736 sheets of paper for 62 copies
Step-by-step explanation:
12 + 16 = 28
28 x 62 = 1736
So, your answer is 1736 :)
Use the distributive property to multiply (3w + 5)(–2w – 7).
-6w^2+31w+35
6w^2-21w-35
-6w^2-31w-35
6w^2-21w+30
Answer:
\(=-6w^2-31w-35\)
Step-by-step explanation:
Apply Foil.
\(\left(3w+5\right)\left(-2w-7\right)=3w\left(-2w\right)+3w\left(-7\right)+5\left(-2w\right)+5\left(-7\right)\)
\(=3w\left(-2w\right)+3w\left(-7\right)+5\left(-2w\right)+5\left(-7\right)\)
\(=-6w^2-31w-35\)
Carrie and nine of her friends go out to dinner. The total bill comes to $191.10. They decide to (I leave a 15% tip. Each person will contribute an equal amount to the total tip. Estimate what each person should contribute.
$19.00
$28.50
$1.90
$2.85
Answer:
$2.85 per person
Step-by-step explanation:
$191.10 * 0.15 = $28.665 tip
total tip divide by 10 people
$28.665/10 = $2.85
Each person has to contribute $2.85 amount for the tip.
Given,
Total no. of person go out for dinner = carrie + her nine friends
= 1+9 = 10
Amount of the bill is = $191.10
Amount of tip is = 15% of the bill
= \(\frac{15 }{100}\) × $ 191.10
= 28.665
Total amount each person contribute an equal amount for tip is = \(\frac{28.665}{10}\)
=$ 2.85
Each person contribute $2.85 amount for the tip.
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Which of the following options have the same value as 80%, percent of 22?
Answer:
A
D
E
is the correct answer
Answer:
A
D
E
Step-by-step explanation: it was right on khan academy so I think it is right
(20x^3-7x^2+3x-7)/-13x^2-5
Answer:
x = ((30 sqrt(1462809) + 36253)^(2/3) - 131)/(60 (30 sqrt(1462809) + 36253)^(1/3)) + 7/60 or x = 7/60 - 1/60 ((-1)/(30 sqrt(1462809) + 36253))^(1/3) (131 (-1)^(1/3) + (30 sqrt(1462809) + 36253)^(2/3)) or x = 1/60 (131 (-1/(36253 + 30 sqrt(1462809)))^(1/3) + (-1)^(2/3) (36253 + 30 sqrt(1462809))^(1/3)) + 7/60
see atachement it's more legible.
Step-by-step explanation:
Solve for x:
(20 x^3 - 7 x^2 + 3 x - 7)/(-13 x^2 - 5) = 0
Hint: | Multiply both sides by a polynomial to clear fractions.
Multiply both sides by -13 x^2 - 5:
20 x^3 - 7 x^2 + 3 x - 7 = 0
Hint: | Look for a simple substitution that eliminates the quadratic term of 20 x^3 - 7 x^2 + 3 x - 7.
Eliminate the quadratic term by substituting y = x - 7/60:
-7 + 3 (y + 7/60) - 7 (y + 7/60)^2 + 20 (y + 7/60)^3 = 0
Hint: | Write the cubic polynomial on the left hand side in standard form.
Expand out terms of the left hand side:
20 y^3 + (131 y)/60 - 36253/5400 = 0
Hint: | Write the cubic equation in standard form.
Divide both sides by 20:
y^3 + (131 y)/1200 - 36253/108000 = 0
Hint: | Perform the substitution y = z + λ/z.
Change coordinates by substituting y = z + λ/z, where λ is a constant value that will be determined later:
-36253/108000 + (131 (z + λ/z))/1200 + (z + λ/z)^3 = 0
Hint: | Transform the rational equation into a polynomial equation.
Multiply both sides by z^3 and collect in terms of z:
z^6 + z^4 (3 λ + 131/1200) - (36253 z^3)/108000 + z^2 (3 λ^2 + (131 λ)/1200) + λ^3 = 0
Hint: | Find an appropriate value for λ in order to make the coefficients of z^2 and z^4 both zero.
Substitute λ = -131/3600 and then u = z^3, yielding a quadratic equation in the variable u:
u^2 - (36253 u)/108000 - 2248091/46656000000 = 0
Hint: | Solve for u.
Find the positive solution to the quadratic equation:
u = (36253 + 30 sqrt(1462809))/216000
Hint: | Perform back substitution on u = (36253 + 30 sqrt(1462809))/216000.
Substitute back for u = z^3:
z^3 = (36253 + 30 sqrt(1462809))/216000
Hint: | Take the cube root of both sides.
Taking cube roots gives 1/60 (36253 + 30 sqrt(1462809))^(1/3) times the third roots of unity:
z = 1/60 (36253 + 30 sqrt(1462809))^(1/3) or z = -1/60 (-36253 - 30 sqrt(1462809))^(1/3) or z = 1/60 (-1)^(2/3) (36253 + 30 sqrt(1462809))^(1/3)
Hint: | Perform back substitution with y = z - 131/(3600 z).
Substitute each value of z into y = z - 131/(3600 z):
y = 1/60 (30 sqrt(1462809) + 36253)^(1/3) - 131/(60 (30 sqrt(1462809) + 36253)^(1/3)) or y = -1/60 (-30 sqrt(1462809) - 36253)^(1/3) - (131 (-1)^(2/3))/(60 (30 sqrt(1462809) + 36253)^(1/3)) or y = 131/60 ((-1)/(30 sqrt(1462809) + 36253))^(1/3) + 1/60 (-1)^(2/3) (30 sqrt(1462809) + 36253)^(1/3)
Hint: | Simplify each solution.
Bring each solution to a common denominator and simplify:
y = ((30 sqrt(1462809) + 36253)^(2/3) - 131)/(60 (36253 + 30 sqrt(1462809))^(1/3)) or y = -1/60 (-1/(36253 + 30 sqrt(1462809)))^(1/3) ((30 sqrt(1462809) + 36253)^(2/3) + 131 (-1)^(1/3)) or y = 1/60 (131 ((-1)/(30 sqrt(1462809) + 36253))^(1/3) + (-1)^(2/3) (30 sqrt(1462809) + 36253)^(1/3))
Hint: | Perform back substitution on the three roots.
Substitute back for x = y + 7/60:
Answer: x = ((30 sqrt(1462809) + 36253)^(2/3) - 131)/(60 (30 sqrt(1462809) + 36253)^(1/3)) + 7/60 or x = 7/60 - 1/60 ((-1)/(30 sqrt(1462809) + 36253))^(1/3) (131 (-1)^(1/3) + (30 sqrt(1462809) + 36253)^(2/3)) or x = 1/60 (131 (-1/(36253 + 30 sqrt(1462809)))^(1/3) + (-1)^(2/3) (36253 + 30 sqrt(1462809))^(1/3)) + 7/60
Before Buddy the Elf goes crazy pushing all of the buttons on the elevator, only 4 buttons are lit up out of 79 floors. About what percent is this?
Can anyone help a girl out?
Answer:
5%
Step-by-step explanation:
DIvide 4 by 79
Solve 3(a + 3) – 6 = 21.
Answer:
a=6
Step-by-step explanation:
to find the value of a you need to simplify the equation first. so...
3(a+3)-6=21 (you remove the bracket first)
3a+9-6=21
3a+3=21 (you collect the like terms then)
3a=21-3
3a=18 (then you both divide both sides by 3 to find the value of a)
a=18/3
a=6
to check your answer substitute 3 instead of a
3(a+3)-6=21
3(6+3)-6=21
3(9)-6=21 (according to BODMAS since multiplication comes first you multiply 3 with 9 before subtracting it from 6.)
29-6=21
21=21
Answer:6
Step-by-step explanation:
3(a + 3) - 6 = 21
3(a + 3) = 21 + 6
3(a + 3) =27
a + 3. = 27 ÷ 3
a + 3. = 9
a. = 9 - 3
a. = 6
Consider the polynomial
(4mn^2n - 2mn + 6) + (6mn^2 - 1) - (mn^2 - 2 + 9mn)
Combine all like terms and enter the coefficients for each term into the blanks below
The required coefficients are:4, -1, -11, and 7.
Coefficients refer to the numerical values that are assigned to variables in mathematical equations, models, or formulas. They indicate the relative importance or contribution of each variable in the equation. Coefficients are used to determine the relationship between variables and are often estimated through statistical analysis or optimization techniques.
In algebraic equations, coefficients are the numbers multiplied by variables. For example, in the equation 2x + 3y = 5, the coefficients are 2 and 3.
In statistical models, such as linear regression, coefficients represent the slopes or weights assigned to the predictor variables. These coefficients indicate how much the response variable is expected to change for a unit change in the corresponding predictor variable, assuming all other variables are held constant.
We need to consider the polynomial:
(4mn^2n - 2mn + 6) + (6mn^2 - 1) - (mn^2 - 2 + 9mn)
To combine the like terms and find the coefficients of each term, we can write the polynomial in the following form:
4mn^2n - 2mn + 6 + 6mn^2 - 1 - mn^2 + 2 - 9mn
Taking the coefficients of the terms with "mn^2"4mn^2n - mn^2
Taking the coefficients of the terms with "mn"-2mn - 9mn = -11mn
Taking the coefficients of the constant terms6 + 2 - 1 = 7
Therefore, the required coefficients are:4, -1, -11, and 7.
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Is 3/4 ÷ 1/2 the same as 1/2 ÷ 3/4?
Answer:
I believe it is false
Step-by-step explanation:
Select all the true statements
The true statements are;
1) AB + BC = AC
Length of BC = |6 - 1|
2) ∠JMK = 50°
∠KML = 35°
How to Interpret Number Line intervals?
1) From the given number line interval, we can deduce the interpretation as follows;
AB + BC = AC
Length of BC = 5 units or |6 - 1|
Length of B = 3 Units
2) We can see that ∠JML is an angle triangle. Thus, ∠JML = 85°. Thus;
6x + 2 + 4x + 3 = 85
10x + 5 = 85
10x = 85 - 5
10x = 80
x = 80/10
x = 8°
Thus;
∠JMK = 6(8) + 2
∠JMK = 50°
∠KML = 85° - 50°
∠KML = 35°
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Which is an example of discrete data?
A)
speed of a train
B)
number of passengers on a train
weight of a passenger car on a train
D)
amount of fuel in the train's engine
Answer:
I think it's B
Step-by-step explanation:
Just thinking
thirty-six divided by six
Answer:
6
Step-by-step explanation:
tion. Then. determine how many books she will have after 4 years.
Answer:2x3x4
Step-by-step explanation:
Can someone help me with these math problems?
A manufacturer knows that their items have a normally distributed lifespan, with a mean of 13.9 years, and standard deviation of 2.9 years. If you randomly purchase 9 items, what is the probability that their mean life will be longer than 14 years
Answer:
0.4588
Step-by-step explanation:
When we have random sample, the z score formula we use is:
z = (x-μ)/σ/√n
where x is the raw score = 14
μ is the population mean = 13.9
σ is the population standard deviation = 2.9
n is random number of samples = 9
z = 14 - 13.9/2.9/√9
z = 0.1/2.9/3
z = 0.10345
Probability value from Z-Table:
P(x<14) = 0.5412
P(x>14) = 1 - P(x<14) = 0.4588
The probability that their mean life will be longer than 14 years is 0.4588
A manufacturer produces a commodity where the length of the commodity has approximately normal distribution with a mean of 13.2 inches and standard deviation of 2.3 inches. If a sample of 37 items are chosen at random, what is the probability the sample's mean length is greater than 12.1 inches? Round answer to four decimal places.
The probability that the sample's mean length is greater than 6.3 inches is0.8446.
Here, we have,
Given mean of 6.5 inches, standard deviation of 0.5 inches and sample size of 46.
We have to calculate the probability that the sample's mean length is greater than 6.3 inches is 0.8446.
Probability is the likeliness of happening an event.
It lies between 0 and 1.
Probability is the number of items divided by the total number of items.
We have to use z statistic in this question because the sample size is greater than 30.
μ=6.5
σ=0.5
n=46
z=X-μ/σ
where μ is mean and
σ is standard deviation.
First we have to find the p value from 6.3 to 6.5 and then we have to add 0.5 to it to find the required probability.
z=6.3-6.5/0.5
=-0.2/0.5
=-0.4
p value from z table is 0.3446
Probability that the mean length is greater than 6.3inches is 0.3446+0.5=0.8446.
Hence the probability that the mean length is greater than 6.3 inches is 0.8446.
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Bryan invests $500 in an account earning 4% interest that compounds annually. If hemakes no additional deposits or withdrawals, how much will be in the account:1. After 10 years?
Using the compound interest formula:
\(\begin{gathered} A=P(1+\frac{r}{n})^{nt} \\ _{\text{ }} \\ _{} \end{gathered}\)Where:
P = Principal = 500
r = interest rate = 4% = 0.04
n = Number of times interest is compounded per year = 1
t = time = 10
so:
\(\begin{gathered} A=500(1+\frac{0.04}{1})^{10\cdot1} \\ A\approx740.12 \end{gathered}\)Answer:
$740.12
Which graph represents a function with direct variation? A coordinate plane with a line passing through (negative 4, 0) and (0, negative 2). A coordinate plane with a line passing through (negative 5, 4) and (0, 3). A coordinate plane with a line passing through (negative 4, negative 6) and (0, 3). A coordinate plane with a line passing through (negative 1, negative 4), (0, 0) and (1, 4).
A line passing through the points (-1,-4),(0,0) and (1,4).
The correct option is (B).
What is graph?Graph is a mathematical representation of a network and it describes the relationship between lines and points.
The only line that passes through origin is having coordinates (-1,-4),(0,0) and (1,4).
m= y/x
m = -4/-1
m=4
Hence, the linear equation is y=4x, which represent in direct variation.
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Answer:
C
Step-by-step explanation:
If the line is a direct variation it has to go through the origin
Suppose you plan to sell five trading cards. Three of the cards
will be shipped domestically, and two will be shipped
internationally. The cost of international shipping is $2.50
greater than the cost of domestic shipping.
Write About It!
If you spent $22.50 on shipping, how much is the cost of
domestic shipping? Define a variable, write an equation,
and solve the problem.
Answer: $3.50
Step-by-step explanation:
Let the cost of domestic shipping be x.
Since the cost of international shipping is $2.50 greater than the cost of domestic shipping. This will be:
= x + 2.50
Since we are further told that three of the cards will be shipped domestically, and two will be shipped internationally and that $22.50 will be spent on shipping, this will be express in an equation as:
3x + 2(x + 2.50) = 22.50
3x + 2x + 5.00 = 22.50
5x = 22.50 - 5.00
5x = 17.50
x = 17.50/5
x = $3.50
The cost if domestic shipping is $3.50
The distance from Cory's home to the library is 2 6 mile. Which point is at 2 6 on the number line?
As a result, the point on the number line that represents 10 miles would be much more to the right and outside the bounds of the image.
What is the example's line number?The line number 10.12, for instance, refers to page 10, line 12. The part of the line number to the left of the period is referred to as the "page" or "part," and the part to the right is referred to as the "line."
What is number line defined simply?A number line is a representation of numbers along a straight line. It acts as a template for grouping and contrasting numbers. Any real number, including all whole numbers and natural numbers, can be represented by it.
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Question:
The distance from Cory's home to the library is mile. Which point is at on the number line?
A. Point A
B. Point B
C. Point C
D. Point D
g(n) = n + 2; Find g(6)
Answer:
g(6)=8
Step-by-step explanation
they give you that the value of n is 6 so substitute it into the equation and solve. g(6)=6+2
g(6)=8
11 less than the quotient of
4
44 and
�
xx.
The expression which is used to represents the statement "one-more than the quotient of a number x" and 4 is "x/4 + 1".
A "Quotient" is the result of a division operation between two numbers, where one number is divided by another. It represents the number of times one number is contained within another number.
An "Expression" is defined as "mathematical-phrase" which contain numbers, variables, and operators such as addition, subtraction, multiplication, and division. It can also contain functions and other mathematical symbols.
The quotient of a number"x" and 4 can be written as x/4.
So, one more than the quotient of a number x and 4 can be represented by the expression:
⇒ x/4 + 1,
Therefore, required mathematical expression is "x/4 + 1".
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The given question is incomplete, the complete question is
Write an expression to represent : One more than the quotient of a number x and 4.
The side of a cube is measured as 11.4 centimeters with a possible error of + - (positive and negative) 0.04 centimeters. Give an estimate for the possible error in the value of the volume of the cube.
Answer: _________ cubic cm
Answer:
The volume of a cube is given by the formula V = s^3, where s is the length of a side of the cube. In this case, the length of a side is 11.4 centimeters with a possible error of + - 0.04 centimeters.
To find the possible error in the value of the volume of the cube, we can use the formula for the maximum error in a product:
max error in V = |V| * (max error in s / s)
where |V| is the absolute value of the volume, and max error in s is the maximum possible error in the measurement of the side.
Substituting the given values, we get:
max error in V = |11.4^3| * (0.04 / 11.4)
max error in V = 538.516 * 0.00351
max error in V = 1.89 cubic centimeters (rounded to two decimal places)
Therefore, the estimate for the possible error in the value of the volume of the cube is 1.89 cubic centimeters
What is the measure of
Answer:
B. 108
Step-by-step explanation:
What is the FORMULA for the VOLUME of a CONE?
Answer:
V = 1/3 * π * r^2 * h OR V = π * r^2 * h/3
Step-by-step explanation:
hope it will help you dear
you told only formula if you need derevation then say :)
Fifty random shoppers at an electronics store have been interviewed and 35 of them intend to purchase a newly released smart phone. What probability distribution describes this situation and what are its mean and standard deviation of phone sales if we are concerned about 1071 shoppers that day
Answer:
We use the binomial distribution to describe this situation.
The mean number of phone sales is 749.7 with a standard deviation of 15.
Step-by-step explanation:
For each shopper, there are only two possible outcomes. Either they plan to purchase the newly released smart phone, or they do not. Each customer is independent of other customers. So we use the binomial distribution to solve this question.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The expected value of the binomial distribution is:
\(E(X) = np\)
The standard deviation of the binomial distribution is:
\(\sqrt{V(X)} = \sqrt{np(1-p)}\)
Fifty random shoppers at an electronics store have been interviewed and 35 of them intend to purchase a newly released smart phone.
This means that \(p = \frac{35}{50} = 0.7\)
What are its mean and standard deviation of phone sales if we are concerned about 1071 shoppers that day
1071 shoppers, so \(n = 1071\)
Mean
\(E(X) = 1071*0.7 = 749.7\)
Standard deviation
\(\sqrt{V(X)} = \sqrt{1071*0.7*0.3} = 15\)
The mean number of phone sales is 749.7 with a standard deviation of 15.
2 Select the correct answer. A circle with radius 5 and center A. The coordinates of the center of the circle are (-3, 12). What is the general form of the equation of the given circle with center A? A. x2 + y2 + 6x − 24y − 25 = 0 B. x2 + y2 − 6x + 24y + 128 = 0 C. x2 + y2 + 6x – 24y + 128 = 0 D. x2 + y2 + 6x − 24y + 148 = 0 Reset Next
The correct equation is D. x2 + y2 + 6x − 24y + 148 = 0.
What is equation?Equation is a physical and mathematical statement that describing physical phenomena and the relationship between different physical quantity typically consist of variable simple presenting physical quantity and then it personal variable may be pointed such as your energy.
This equation is the general form of a circle with center A and radius 5. The equation can be derived from the coordinates of the center A and the radius of the circle. The center of the circle is located at (-3, 12). To get the equation, first calculate the distance between the center A and a point on the circumference of the circle, which is the radius of the circle, 5. Then, use the Pythagorean theorem to calculate the equation of the circle: x2 + y2 + 6x – 24y + 148 = 0.
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What are the domain and range of the function?
f(x) =1/3x^7
The correct answer would be an option (B) the domain and range of the function i.e.
The domain is (-∞, 0) U (0, ∞)
The range is (-∞, 0) U (0, ∞)
What are the domain and range of the function?The domain of the function includes all possible x values of a function, and the range includes all possible y values of the function.
Given function that f(x) = 1 / (3x)⁷
Any x value that makes the denominator zero is excluded from the domain.
Let's determine any excluded x value.
⇒ 3x⁷ = 0
Divide both sides by 3.
⇒ x⁷ = 0
Take the 7th root of both sides.
⇒ x = 0
So the only excluded x value is 0 .
Thus, the domain is (-∞, 0) U (0, ∞)
Whatever the big or small value of an x we substitute in, f(x) cannot be zero.
The range is (-∞, 0) U (0, ∞)
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The graph below shows the total amount, y, that an electrician charges for a service call that lasts x hours.
Which of the following is the rate of change in the total amount charged with respect to the time spent on the service call?
Question 5 options:
$25 per hour
$0.04 per hour
$65 per hour
$40 per hour
The rate of change in the total amount charged with respect to the time spent on the service call is $40 per hour.
What is the rate of change?The mathematical concept of rate of change describes how much one quantity changes in relation to another. It is calculated as the difference between the change in the output (the dependent variable) and the change in the input (independent variable).
The rate of change, in other words, informs us of how quickly or slowly something is changing through time or in relation to another variable. When tracking the distance an automobile travels over time, for instance, the rate of change would be the car's speed, which is calculated as the distance traveled divided by the time required.
Slope, which is the ratio of the vertical change (rise) to the horizontal change (run) between two points on a graph, is a common way to depict the rate of change. The rate of change of the dependent variable with respect to the independent variable is depicted by the slope of a straight-line graph.
The rate of change in the total amount charged with respect to the time spent on the service call represents the slope of the graph. We can find the slope of the graph by taking any two points on the line and calculating the change in y (total amount) divided by the change in x (time spent on the service call).
Looking at the graph, we can choose two points: (2, 130) and (8, 370). The change in y is:
370 - 130 = 240
And the change in x is:
8 - 2 = 6
Therefore, the slope (rate of change) of the graph is:
240/6 = 40
So the rate of change in the total amount charged with respect to the time spent on the service call is $40 per hour.
Therefore, the correct option is $40 per hour.
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(a) In a sale, the price of a car was reduced from $ 17 000 to $ 15 300. Calculate the reduction as a percentage of the original price.
Answer:
reduction = 17000-15300= 1700
precentage of original price = 1700÷ 17000×100
=10%
Non Shaded Shaded
Area
Area
8
Find the radius
of the small circle
Answer:
The answer is 16pi or 50.3cm² to 1 d.p
Step-by-step explanation:
The non shaded=area of shaded
d=8
r=d/2=4
A=pir³
A=p1×4²
A=pi×16
A=16picm² or 50.3cm² to 1d.p
Answer:
3.45 cm (3 s.f.)
Step-by-step explanation:
We have been given a 5-sided regular polygon inside a circumcircle. A circumcircle is a circle that passes through all the vertices of a given polygon. Therefore, the radius of the circumcircle is also the radius of the polygon.
To find the radius of a regular polygon given its side length, we can use this formula:
\(\boxed{\begin{minipage}{6 cm}\underline{Radius of a regular polygon}\\\\$r=\dfrac{s}{2\sin\left(\dfrac{180^{\circ}}{n}\right)}$\\\\\\where:\\\phantom{ww}$\bullet$ $r$ is the radius.\\ \phantom{ww}$\bullet$ $s$ is the side length.\\\phantom{ww}$\bullet$ $n$ is the number of sides.\\\end{minipage}}\)
Substitute the given side length, s = 8 cm, and the number of sides of the polygon, n = 5, into the radius formula to find an expression for the radius of the polygon (and circumcircle):
\(\begin{aligned}\implies r&=\dfrac{8}{2\sin\left(\dfrac{180^{\circ}}{5}\right)}\\\\ &=\dfrac{4}{\sin\left(36^{\circ}\right)}\\\\ \end{aligned}\)
The formulas for the area of a regular polygon and the area of a circle given their radii are:
\(\boxed{\begin{minipage}{6 cm}\underline{Area of a regular polygon}\\\\$A=\dfrac{nr^2\sin\left(\dfrac{360^{\circ}}{n}\right)}{2}$\\\\\\where:\\\phantom{ww}$\bullet$ $A$ is the area.\\\phantom{ww}$\bullet$ $r$ is the radius.\\ \phantom{ww}$\bullet$ $n$ is the number of sides.\\\end{minipage}}\)
\(\boxed{\begin{minipage}{6 cm}\underline{Area of a circle}\\\\$A=\pi r^2$\\\\where:\\\phantom{ww}$\bullet$ $A$ is the area.\\\phantom{ww}$\bullet$ $r$ is the radius.\\\end{minipage}}\)
Therefore, the area of the regular pentagon is:
\(\begin{aligned}\textsf{Area of polygon}&=\dfrac{5 \cdot \left(\dfrac{4}{\sin\left(36^{\circ}\right)}\right)^2\sin\left(\dfrac{360^{\circ}}{5}\right)}{2}\\\\&=\dfrac{5 \cdot \left(\dfrac{4}{\sin\left(36^{\circ}\right)}\right)^2\sin\left(72^{\circ}\right)}{2}\\\\&=\dfrac{\dfrac{80\sin\left(72^{\circ}\right)}{\sin^2\left(36^{\circ}\right)}}{2}\\\\&=\dfrac{40\sin\left(72^{\circ}\right)}{\sin^2\left(36^{\circ}\right)}\\\\&=110.110553...\; \sf cm^2\end{aligned}\)
The area of the circumcircle is:
\(\begin{aligned}\textsf{Area of circumcircle}&=\pi \left(\dfrac{4}{\sin\left(36^{\circ}\right)}\right)^2\\\\&=\dfrac{16\pi}{\sin^2\left(36^{\circ}\right)}\\\\&=145.489779...\; \sf cm^2\end{aligned}\)
The area of the shaded area is the area of the circumcircle less the area of the regular pentagon plus the area of the small central circle.
The area of the unshaded area is the area of the regular pentagon less the area of the small central circle.
Given the shaded area is equal to the unshaded area:
\(\begin{aligned}\textsf{Shaded area}&=\textsf{Unshaded area}\\\\\sf Area_{circumcircle}-Area_{polygon}+Area_{circle}&=\sf Area_{polygon}-Area_{circle}\\\\\sf 2\cdot Area_{circle}&=\sf 2\cdot Area_{polygon}-Area_{circumcircle}\\\\2\pi r^2&=2 \cdot \dfrac{40\sin\left(72^{\circ}\right)}{\sin^2\left(36^{\circ}\right)}-\dfrac{16\pi}{\sin^2\left(36^{\circ}\right)}\\\\2\pi r^2&=\dfrac{80\sin\left(72^{\circ}\right)}{\sin^2\left(36^{\circ}\right)}-\dfrac{16\pi}{\sin^2\left(36^{\circ}\right)}\\\\\end{aligned}\)
\(\begin{aligned}2\pi r^2&=\dfrac{80\sin\left(72^{\circ}\right)-16\pi}{\sin^2\left(36^{\circ}\right)}\\\\r^2&=\dfrac{40\sin\left(72^{\circ}\right)-8\pi}{\pi \sin^2\left(36^{\circ}\right)}\\\\r&=\sqrt{\dfrac{40\sin\left(72^{\circ}\right)-8\pi}{\pi \sin^2\left(36^{\circ}\right)}}\\\\r&=3.44874763...\sf cm\end{aligned}\)
Therefore, the radius of the small circle is 3.45 cm (3 s.f.).