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2 years ago

11

Is this the right answer?

1 answer:

pychu [463]2 years ago

6 0

Looks correct to me but i'm not 100% sure

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A researcher wishes to estimate the percentage of adults who support abolishing the penny. What size sample should be obtained i

Scorpion4ik [409]

Answer:

a) We need a sample size of at least 3109.

b) We need a sample size of at least 4145.

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:

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

99% confidence level

So $\alpha = 0.01$ , z is the value of Z that has a pvalue of $1 - \frac{0.01}{2} = 0.995$ , so $Z = 2.575$ .

(a) he uses a previous estimate of 25%?

we need a sample of size at least n.

n is found when $M = 0.02, \pi = 0.25$ . So

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

$0.02 = 2.575\sqrt{\frac{0.25*0.75}{n}}$

$0.02\sqrt{n} = 2.575\sqrt{0.25*0.75}$

$\sqrt{n} = \frac{2.575\sqrt{0.25*0.75}}{0.02}$

$(\sqrt{n})^{2} = (\frac{2.575\sqrt{0.25*0.75}}{0.02})^{2}$

$n = 3108.1$

We need a sample size of at least 3109.

(b) he does not use any prior estimates?

When we do not use any prior estimate, we use $\pi = 0.5$

So

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

$0.02 = 2.575\sqrt{\frac{0.5*0.5}{n}}$

$0.02\sqrt{n} = 2.575\sqrt{0.5*0.5}$

$\sqrt{n} = \frac{2.575\sqrt{0.5*0.5}}{0.02}$

$(\sqrt{n})^{2} = (\frac{2.575\sqrt{0.5*0.5}}{0.02})^{2}$

$n = 4144.1$

Rounding up

We need a sample size of at least 4145.

8 0

3 years ago

You are at a campus party where there are a total number of n people. The host asked everyone to put their phones in a bowl whil

kirill [66]

Answer:

1, $\frac{m}{n}$ , $\frac{1-m}{n}$ .

Step-by-step explanation:

probability = $\frac{Number of Possible Outcomes}{Total Outcomes}$

Total number of persons in the party = n

a) Pr ( every person gets their phone back) = Pr (each person picks his phone ) multiplied by number of person

= $\frac{1}{n}$ × n = 1.

No of first m persons to pick = m

No of last m persons to pick = 1 - m

b) Pr (first m persons to pick each gets their phones back) = $\frac{m}{n}$

c) Pr( first m persons get a phone belonging to last m persons) = $\frac{1-m}{n}$

3 0

3 years ago

-5, 3, -2, 1, -1, 0 how do I find the answer

-Dominant- [34]

Answer:

answer for what...there isnt a question...

7 0

3 years ago

Read 2 more answers

To make 3/4 pound of mixed nuts, how many pounds of cashews would you add to 1/8 pound of almonds and 1/4 pound of peanuts?

Anna11 [10]

you will need 3/8 pounds of peanut.

3/8 + 1/4 + 1/8= 3/4

(ask me if you are confuse plz)

7 0

3 years ago

each paperclip is 7/8 of an inch long and costs $.03. exactly enough paper clips are laid end to end yo have a total length of 5

GalinKa [24]

1 clipe..............7/8
x.......................56

7x/8 = 56
7x = 56*8
x = 56*8/7
x = 8*8
x = 64 clipes

1 clipe = 0,03
64 clipes = 0,03*64
64 clipes = 1,92

5 0

2 years ago