1. A continuous random variable x produces a right-skewed distribution with a mean of 25 and a standard deviation of 6. The sampling distribution of the sample mean for a sample of 45 elements taken from this population is:

approximately normal

normal

skewed to the right

skewed to the left

1. Which of the following conditions is not required to use the t distribution to make a confidence interval for the population mean?

the population from which the sample is drawn is (approximately) normally distributed

the sample size is less than 30

the population from which the sample is drawn has a t distribution

the population standard deviation is unknown

1. Population standard deviation unknown. A sample of 27 elements produced a mean of 124 and a standard deviation of 16. Assuming that the population has a normal distribution, the 98% confidence interval for the population mean is:

115.44 to 132.44

117.50 to 130.50

114.25 to 133.75

116.37 to 131.63

1. In a test of hypothesis, the probability of committing a Type I error is called the:

confidence level

confidence interval

significance level

beta error

1. A researcher wants to test if the mean annual salary of all lawyers in a city is different from $110,000. The alternative hypothesis for this sample will be that the population mean is:

• equal to $110,000

less than $110,000

not equal to $110,000

greater than $110,000

1. For a one-tailed test, the probability value (p-value) is:

• the area under the curve between the mean and the observed value of the sample statistic
• twice the area under the curve between the mean and the observed value of the sample statistic
• the area in the tail beyond the observed value of the sample statistic
• twice the area in the tail beyond the observed value of the sample statistic

1. In a test of hypothesis, the null hypothesis is that the population mean is equal to 37 and the alternative hypothesis is that the population mean is less than 37. A sample of 81 elements selected from the population produced a mean of 35.49 and a standard deviation of 4.59. What is the approximate p-value for this test?

.0060

.0235

.0015

.0030