1. Jim takes a simple random sample of 15 from a very large population whose variance is unknown. She intends to perform a one-tail test for the mean, so draws a boxplot of the sample values and finds that distribution of the sample values is roughly symmetrical. She is justified in using:
A.t-test because the sample is small
B.t-test because the sample is normally distributed
C.t-test because the population standard deviation is unknown
D.Z-test because the sample is normally distributed and population is very large
2. A medical researcher contends that lung capacity varies significantly between smokers and nonsmokers. The mean capacity of a sample of 30 nonsmokers is 5.0 litters with a sample standard deviation of 0.3 liters. What is the p-value for this question if we want to test that lung capacity is larger among nonsmokers (lung capacity of smokers is 4.0 litters)?
A.0%
B.30%
C.0.3%
D.None of the above
3. A Program provides incentives for the use of photovoltaics, solar hot water, and other renewable energy sources. During the last few years it was assumed that approximately 20% of families are interested in the program. However, it is now suspected that this figure has increased. In order to test this, a random sample of 1200 families is selected, and it is found that 360 of them are interested in the program. What are the null and alternative hypotheses that should be used (H0 = null hypothesis and Ha = alternative hypothesis)?
A.H0: p = 360; Ha: p >360
B.H0: p = 30%; Ha: p < 30%
C.H0: p = 20%; Ha: p > 20%
D.H0: p > 30%; Ha: p = 30%
E.H0: p = 30%; Ha: p > 30%