Question

In a recent poll of 1100 randomly selected home delivery truck drivers, 26% said they had encountered an aggressive dog on the job at least once.

part g) Report the 95% confidence interval for the proportion of all home delivery truck drivers who have encountered an aggressive dog on the job at least once. (Round final calculations to the nearest tenth of a percent)

A) (20.7%, 31.3%)

B) (23.4%, 28.6%)

C) (24.7 %, 27.3%)

D) None of these Find the required confidence interval.

part h) A researcher wishes to estimate the proportion of adults in the city of Darby who are vegetarian. In a random sample of 1,643 adults from this city, the proportion that are vegetarian is 0.051. Find a 95% confidence interval for the proportion of all adults in the city of Darby that are vegetarians.

A) (0.0404, 0.0616)

B) (0.0434, 0.0586)

C) (0.0268, 0.0752)

D) (0.0456, 0.0564)

Solve the problem.

part I) The weights at birth of five randomly chosen baby giraffes were 111, 115, 120, 103, and 106 pounds. Assume the distribution of weights is normally distributed. Find a 95% confidence interval for the mean weight of all baby giraffes. Use technology for your calculations. Give the confidence interval in the form "estimate ± margin of error." Round to the nearest tenth of a pound.

A) There is not enough information given to calculate the confidence interval.

B) 111.0 ± 8.5 pounds

C) 111.5 ± 9.0 pounds

D) 110.0 ± 8.5 pounds

Feature movie lengths (in hours) were measured for all movies shown in the past year in the U.S. The mean length of all feature length movies shown was 1.80 hours with a standard deviation of 0.15 hours. Suppose the length of a random sample of 20 movies was recorded from all movies released this year. The mean length of the feature length movies was found to be 1.72 hours with a standard deviation of 0.18 hours.

part K) What is the standard error for the estimated mean feature length movie time of the 20 randomly selected movies? Round to the nearest thousandth.

A) 0.034

B) 0.040

C) 0.055

D) 0.356

Answer 1

g)

sample success x =		286
sample size          n=		1100
sample proportion p̂ =x/n=		0.2600
std error se= √(p*(1-p)/n) =		0.0132
for 95 % CI value of z=		1.960
margin of error E=z*std error   =		0.0259
lower bound=p̂ -E                       =		0.2341
Upper bound=p̂ +E                     =		0.286

B) (23.4%, 28.6%)

h)

A) (0.0404, 0.0616)

i)

B) 111.0 ± 8.5 pounds

k)

sample size    n=	20.00
std deviation σ=	0.150
std error ='σx=σ/√n=	0.034