1.A researcher wishes to determine the difference in two population means. To do this, she randomly samples 9 items from each population and calculates a 90% confidence interval. The sample from the first population produces a mean of 780 with a standard deviation of 240. The sample from the second population produces a mean of 890 with a standard deviation of 280. Assume that the values are normally distributed in each population. The critical value for this test is _______.

2.Suppose that there is no difference in the population means of two populations. Suppose also that the variance of the first population is 28 and the variance of the second population is 30. A random sample of size 49 is drawn from the first population and a random sample of size 36 is drawn from the second population. What is the standard deviation for the sampling distribution of the differences in sample means?

3.

A marketing firm asked a random set of married and single men as to how much money they were willing to spend for a vacation. Test at = 0.05, is there a difference in the two amounts?

	Married men	Single men
Sample size	50	50
Mean spending	380	325
Sample variance	6000	9000

Assume that the population from which the samples are taken are normally distributed and the population variances are not equal.

The critical value for the test is:

4.Restaurateur, Daniel Valentine, is evaluating two sites, Port Douglas and Mission Beach, for his next restaurant. He wants to prove that Port Douglas residents (population 1) dine out more often than Mission Beach residents (population 2). Denny plans to test this hypothesis using a random sample of 81 families from each town. His alternate hypothesis is __________.

5.

According to a magazine, children (ages 2-11) spend an average of 21 hrs 30 mins watching TV per week while teens (ages 12-17) spend an average of 20 hrs 40 mins. Based on the sample statistics obtained below, what is the test value to test that there is significant difference in average television watching times between the two groups.

	Children	Teens
sample mean sample variance sample size	22.45 16.4 15	18.50 18.2 15