1. Researchers compared two groups of competitive rowers: a group of skilled rowers and a group of novices. The researchers measured the angular velocity of each subject's right knee, which describes the rate at which the knee joint opens as the legs push the body back on the sliding seat. The sample size n, the sample means, and the sample standard deviations for the two groups are given below.
The researchers wished to test the hypotheses
H0:the mean knee velocities for skilled and novice rowers are the same.
Ha:the mean knee velocity for skilled rowers is larger than for novice rowers.
The data showed no strong outliers or strong skewness so the researchers decided to use the two-sample t test. The value of the t test statistic is
A. 3.38.
B. 4.00.
C. 16.00.
2. We would like to know the average amount of time students spend studying for their classes each week. A random sample of 100 students are surveyed. They reported spending an average of 7.6 hours studying, with s = 1.2 hours. Based on these data, find a 95% confidence interval for the average amount of time a student studies for classes each week.
A. (7.40, 7.80)
B. (7.36, 7.84)
C. (4.82, 9.58)
3. Researchers compared two groups of competitive rowers: a group of skilled rowers and a group of novices. The researchers measured the angular velocity of each subject's right knee, which describes the rate at which the knee joint opens as the legs push the body back on the sliding seat. The sample size n, the sample means, and the sample standard deviations for the two groups are given below.
The correct test to use to decide if there is a difference in mean leg velocities is a
A. two-sample z test.
B. two-sample t test.
C. pooled two-sample t test.