According to the American Dental Association, 8% of adults have never had a cavity. A dental graduate student contacts an SRS of 1000 adults and calculates the proportion
in this sample who have never had a cavity.
Calculate the mean and standard deviation of the sampling distribution of
.
mean =
standard deviation =
Is the sampling distribution of
approximately Normal? Show work.
(Check shape)
Find the probability that the random sample of 1000 adults will give a result within 2 percentage points of the true proportion.
If the sample size were 9000 rather than 1000, how would this change the shape, center, and variability of the sampling distribution of
?
Shape =
Center =
Variability (S.D.) =
At Westville High School there are 315 seniors and 389 juniors. 65% of the seniors have parking passes and 42% of the juniors have parking passes. The statistics teacher selects an SRS of 30 seniors and a separate SRS of 30 juniors.
Let
be the difference in the sample proportions of seniors and juniors that have parking passes.
What is the shape of the sampling distribution of
? Why?
Find the mean and standard deviation of the sampling distribution of
What is the probability that the difference in sample proportions
(senior – junior) of students with parking passes is greater than 30%?
