1

The Johns Hopkins Regional Talent Searches give the SAT (intended for high school juniors and seniors) to 13-year-olds. In all, 19,883 males and 19,937 females took the tests between 1980 and 1982. The mean scores of males and females on the verbal test are nearly equal, but there is a clear difference between the sexes on the mathematics test. The reason for this difference is not understood. Here are the data.

Groups X S'

Males 416 87

Females 386 74

Give a 99% confidence interval for the difference between the mean score for males and the mean score for females in the population that Johns Hopkins searches.

Question 2

Lisa wants to compare the cost of one- and two-bedroom apartments in Spokane. She collects data for a random sample of 10 advertisements of each type. Here are the rents for the two-bedroom apartments (in dollars per month):

595 500 580 650 675 675 750 500 495 670

Here are the rents for the one-bedroom apartments

500 650 600 505 450 550 515 495 650 395

Find a 95% confidence interval for the additional cost of a second bedroom.

Question 3

Below is the formula we used to construct a 1-sample confidence interval for t. Copy and paste the formula into the answer box and adjust it to construct the 2-sample interval.

xbar +or- * s/sqareroot n