In: Statistics and Probability
In a 2018 poll conducted by SurveyMonkey, they randomly surveyed 368 students
from two- and four-year institutions across the U.S. According to the survey, 58% purchased at
least one of their textbooks on Amazon. What proportion of all U.S. college students purchased
at least one of their textbooks on Amazon?
a. Use StatCrunch to find a 95% confidence interval: _________________
b. Interpret your confidence interval in words.
c. True or False: A 90% confidence interval would be wider than a 95% confidence interval.
d. If the true proportion of all U.S. college students who purchased at least one of their
textbooks on Amazon was 62%, does our confidence interval support or refute it?
using excel>addin>phstat>confidence interval
we ahve
Confidence Interval Estimate for the Proportion | |
Data | |
Sample Size | 368 |
Number of Successes | 213 |
Confidence Level | 95% |
Intermediate Calculations | |
Sample Proportion | 0.58 |
Z Value | -1.9600 |
Standard Error of the Proportion | 0.0257 |
Interval Half Width | 0.0504 |
Confidence Interval | |
Interval Lower Limit | 0.5296 |
Interval Upper Limit | 0.6304 |
a. a 95% confidence interval: (0.5296,0.6304)
b. we are 95% confident that the population proportion of all U.S. college students purchased at least one of their textbooks on Amazon lies in between (0.5296,0.6304)
c. False: A 90% confidence interval would be wider than a 95% confidence interval. because it would be narrower
d. If the true proportion of all U.S. college students who purchased at least one of their
textbooks on Amazon was 62%,yes , confidence interval support or refute it because 0.62 is inside confidence interval