Need help on this question please!

A researcher wants to estimate the percentage of all adults that have used the Internet to seek pre-purchase information in the

Lubov Fominskaja [6]

Answer:

The required sample size for the new study is 801.

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:

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

25% of all adults had used the Internet for such a purpose

This means that $\pi = 0.25$

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 $Z = 1.96$ .

What is the required sample size for the new study?

This is n for which M = 0.03. So

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

$0.03 = 1.96\sqrt{\frac{0.25*0.75)}{n}}$

$0.03\sqrt{n} = 1.96\sqrt{0.25*0.75}$

$\sqrt{n} = \frac{1.96\sqrt{0.25*0.75}}{0.03}$

$(\sqrt{n})^2 = (\frac{1.96\sqrt{0.25*0.75}}{0.03})^2$

$n = 800.3$

Rounding up:

The required sample size for the new study is 801.

4 0

2 years ago

Marta walked at 3.3 miles per hour for 0.54 hours. how far did she walk?

Anon25 [30]

This is a proportion, she is walking 3.3 every hour. She walked for 5.4 hours. And we don't know how far she walked so its x/.54. Then you cross multiply which gives you 3.9×.54=x. We multiply those decimals and we get 1.782.

7 0

3 years ago

if caramel is put onto a sphere-shaped apple such that the surface area increase at a rate of 10 cm2/min, find the rate at which

tresset_1 [31]

Answer:

The diameter will increase at a rate of 1/30π cm/min

Step-by-step explanation:

Here we want to calculate the rate at which the diameter will increase

Mathematically, the area of a sphere is given as;

A = 4πr^2

But r = d/2

so A = 4 * π * d/2 * d/2 = πd^2

dA/d(d) = 2πd

Thus dd/dA = 1/2πd = 1/2 * π * 15 = 1/30π

Given dA/dt = 10

Mathematically;

d(d)/dt = d(d)/dA * dA/dt

dd/dt = 1/30π * 10 = 10/30π = 1/3π cm/min

5 0

3 years ago

Which of the following could NOT be the lengths of the sides of a triangle?

Furkat [3]

Given:

Sides of triangles in the options.

To find:

Which could NOT be the lengths of the sides of a triangle.

Solution:

Condition for triangle:

Sum of two smaller sides of a triangle must be greater than the longest side.

In option A,

$5+5=10>5$

Sides 5 in, 5 in, 5 in are the lengths of the sides of a triangle.

In option B,

$10+15=25>20$

Sides 10 cm, 15 cm, 20 cm are the lengths of the sides of a triangle.

In option C,

$3+4=7>5$

Sides 3 in, 4 in, 5 in are the lengths of the sides of a triangle.

In option D,

$8+5=13$

Since, the sum of two smaller sides is less than the longest side, therefore the sides 8 ft, 15 ft, 5 ft are not the lengths of the sides of a triangle.

Therefore, the correct option is D.

8 0

2 years ago

Select all the statements that are true for the graph shown.

Yuki888 [10]

Answer:

The relationship is proportional.

The relationship is linear.

The equation of the line is y = –3x.

Step-by-step explanation:

The line in the question passes through origin and (4,-12).

The rate of change of the line is