Question

In: Statistics and Probability

1) In a random sample of 61 professional actors, 22 were extroverts. a. Comment on the...

1) In a random sample of 61 professional actors, 22 were extroverts.

a. Comment on the requirements of a confidence interval. b. Find a 90% confidence interval for p.


2) If the average height x is calculated from a random sample of 135 adult Americans, find the probability that the mean height of the sample is between 68 and 70 inches.


3) A food distributor is attempting to deal with complaints that an unacceptable percentage of eggs transported by the company arrive cracked. In a random sample of 325 eggs, 43 are found to be cracked. Calculate a 99% confidence interval for the true population proportion.


4) Suppose we will be computing a 90% confidence interval for a population proportion. Determine the sample size required to produce a margin of error of at most 3 percentage points.

Solutions

Expert Solution

a)as sample is random as well np=22 and n(1-p)=39 both are greater than equal to 10 , therefore requirements for the confidence interval are satisfied

b)

2)

for this mean and std deviation of heights are required

3)

4)

here margin of error E = 0.0300
for90% CI crtiical Z          = 1.645
estimated proportion=p= 0.5000
required sample size n =         p*(1-p)*(z/E)2= 752.00

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