Question 1
The daily water use of homes in a town has mean 310 liters and standard deviation 80 liters. For random samples of 64 homes, what are the mean and standard deviation of the sampling distribution of the sample mean?
AP Statistics Unit 4 review
Unit 4 is 10–20% of Section I. The key decisions are t versus z, paired versus independent, and which tail.
| Weight | 10–20% of the multiple-choice section |
|---|---|
| Topics | 4.1 to 4.10 |
Decisions
- Use t with df = n − 1 for one mean or paired differences.
- Use the two-sample t with the calculator's df for independent groups.
- Small samples need data with no strong skew or outliers.
Try 3 questions
Question 2
Twelve students each took a reading test before and after a summer program. To estimate the mean improvement, which procedure is appropriate?
Question 3
A 95% confidence interval for μ_new − μ_old, the difference in mean battery life (hours) between a new and an old phone model, is (−0.4, 1.8). Which statement is supported?
Next step
Questions people ask
Do you pool variances in AP Statistics?
No. Two-sample t procedures use the unpooled standard error with the calculator's degrees of freedom.