Place the grouping symbols to make this equation true. 84-48/8-4=72

A candidate for a US Representative seat from Indiana hires a polling firm to gauge her percentage of support among voters in he

UkoKoshka [18]

Answer:

a) The minimum sample size is 601.

b) The minimum sample size is 2401.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

The margin of error is:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

For this problem, we have that:

We dont know the true proportion, so we use $\pi = 0.5$ , which is when we are are going to need the largest sample size.

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

a. If a 95% confidence interval with a margin of error of no more than 0.04 is desired, give a close estimate of the minimum sample size that will guarantee that the desired margin of error is achieved. (Remember to round up any result, if necessary.)

This is n for which M = 0.04. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.04 = 1.96\sqrt{\frac{0.5*0.5}{n}}$

$0.04\sqrt{n} = 1.96*0.5$

$\sqrt{n} = \frac{1.96*0.5}{0.04}$

$(\sqrt{n})^2 = (\frac{1.96*0.5}{0.04})^2$

$n = 600.25$

Rounding up

The minimum sample size is 601.

b. If a 95% confidence interval with a margin of error of no more than 0.02 is desired, give a close estimate of the minimum sample size necessary to achieve the desired margin of error.

Now we want n for which M = 0.02. So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.02 = 1.96\sqrt{\frac{0.5*0.5}{n}}$

$0.02\sqrt{n} = 1.96*0.5$

$\sqrt{n} = \frac{1.96*0.5}{0.02}$

$(\sqrt{n})^2 = (\frac{1.96*0.5}{0.02})^2$

$n = 2401$

The minimum sample size is 2401.

4 0

3 years ago

Me need more help plz also add explanation real explanation

Reika [66]

So we want to find the surface area of this pyramid. Finding the surface area of a 3D shape is essentially finding the area of all its sides and adding them together.

What we're going to have to do here is find the area of the base of the pyramid, which is basically a square, and find the area of all four sides of the pyramid, which are triangles.

Formula for area of a square: length × width

Formula for area of a triangle: (base × height) ÷ 2

First we will find the area of the base:

l × w = A

(Write out formula)

8 × 8 =

(Input values)

A = 64 m^2 (square meters or meters squared)

(We have our answer, dont forgot to write your units.)

So we've figured out the area of the base. Now onto the triangles:

(b×h) ÷ 2 = A

(Write out formula)

(8 × 6) ÷ 2 =

(Input values)

48 ÷ 2 =

(Use PEMDAS to solve this correctly. We did whatever was in the parenthesis first, which was multiplication.)

A = 24m^2 (square meters or meters squared)

(We have our answer.)

Now we've found the area of the base of the pyramid and one of the sides of the pyramid, but we're almost done! There's four sides to the pyramid, they're all the same. So since we found the area for one, we can multiply that by 4 to find the area of all sides added together:

24 × 4

(area of a side × total sides)

= 96m^2

All that's left is adding the 96 to the area of the base to get our total surface area of the pyramid:

96 + 64 = 160

The surface area of the pyramid is 160m^2(square meters or meters squared)

(Hope this helps :) )

8 0

3 years ago

Read 2 more answers

What is the surface area of the following figure?

balandron [24]

Answer:

28 cm2

2 x 7 x 2 = 28

hope this helps

8 0

3 years ago

Read 2 more answers

A recent survey determined the IQ score of a random selection of residents of Alaska. The accompanying relative frequency distri

ycow [4]

Answer:

The class width is 20

Step-by-step explanation:

In a frequency or a relative frequency distribution the class width is calculated as the difference between the lower or upper class limits of consecutive classes. A point to note is that all the categories or classes usually have the same class width.

We use the first two classes to calculate the class width by using their respective upper limits;

Class width = 89 - 69

Class width = 20

4 0

3 years ago

Please answer this question only if you know the answer! 30 points and brainliest!

Allisa [31]

Answer:

(4, 3)

Step-by-step explanation:

If this point is reflected about the x-axis, the x-coordinate does not change. The original y-coordiate, -3, becomes +3.

A': (4, 3)

5 0

3 years ago