1. Problem 1
Suppose 40% of registered voters in a certain town are Democrats. You take a simple random sample of 80 voters.
If your survey avoids biases, you expect __________ Democrats, give or take ____________ or so, in your sample.
What is the probability that your sample actually predicts a Republican victory?

2. Problem 2
A student doing a survey at a large university found that her random sample of 160 students reported an average GPA of 3.5 with a standard deviation of The registrar’s office published the average GPA to be Can the difference be explained by sampling variability? If not, how else can it be explained?

3. Problem 3
A simple random sample of size n =70 has a mean of 87 and a sample SD of 0.5.
Find a 98% confidence interval for the population mean.
How important is it that we don’t know the shape of the population?

4. Problem 4
The Motor Vehicle Department plans to estimate the proportion of drivers who have not received any tickets for moving violations during the past three years. How large a sample of its records should it take to be within 0.02 of the true proportion with 99% confidence?

5. Problem 5
Consider the following matched-pair data set. Assume normality of the parent populations. Find a 95% confidence interval for the difference in means. x: y:

6. Problem 6
To determine the effectiveness of a certain vitamin supplement, the weight increase for two groups of mice was measured: Control group: Treatment group: Test at the 5% level of significance whether the vitamins treatment results in a higher weight gain.