Exam 8: Hypothesis Testing

In a particular city, the average annual salary for secretaries is $31,000. A sample of 45 secretaries from Company A shows an average annual salary of $27,500 with a population standard deviation of $5,500. Secretaries at Company A claim they are paid less than the city average. What is the test value for this claim?

A recent survey of gasoline prices indicated that the national average was $4.098 per gallon. The Dallas Automobile Club claimed that gasoline in Texas was significantly lower than the national average. A survey covering 10 different suburbs in Dallas found the average price of gasoline to be $3.924 per gallon with a population standard deviation of $0.053. What critical value should be used to test the claim using α = 0.01?

Using the z table, determine the critical value for the left-tailed test with α = 0.02.

At a certain university, the average cost of books was $320 per student last semester and the population standard deviation was $85. This semester a sample of 55 students revealed an average cost of books of $355 per student. The Dean of Students believes that the costs are greater this semester. What is the test value for this hypothesis?

According to Beautiful Bride magazine, the average age of a groom is now 26.2 years. A sample of 16 prospective grooms in Chicago revealed that their average age was 26.6 years with a standard deviation of 5.3 years. What is the test value for a t test of the claim?

A recent report by the American Medical Association stated the average annual salary of psychiatrists is $189,121 with a population standard deviation of $26,975. A group of hospital administrators randomly sampled 64 psychiatrists and found an average annual salary of $198,630. The group claims that the average annual salary is actually higher than what the American Medical Association reported. What is the P-value for this one-sided test?

Using the z table, determine the critical value for the right-tailed test with α = 0.035.

A lab technician is tested for her consistency by making multiple measurements of the cholesterol level in one blood sample. The target precision is a standard deviation of 1.4 mg/dL or less. If 16 measurements are taken and the standard deviation is 2.1 mg/dL, is there enough evidence to support the claim that her standard deviation is greater than the target, at = .01?

A statistician claims that the standard deviation of the weights of firemen is less than 25 pounds. A sample of 20 randomly chosen firemen had a standard deviation of their weights of 26.2 pounds. Assume the variable is normally distributed. At α = 0.05, what is the critical value χ² for this test?

The probability of a type I error is represented by which of the following symbols?

It has been claimed that at UCLA at least 40% of the students live on campus. In a random sample of 250 students, 90 were found to live on campus. Does the evidence support the claim at = .01?

State whether the null hypothesis should be rejected on the basis of the given P-value. P-value = 0.235, , two-tailed test

Which type of alternative hypothesis is used in the figure below?

In a(n) _____________ test, the null hypothesis should be rejected when the test value is in either of the two critical regions.

Assume that a 90% confidence interval for the mean is . The null hypothesis at 0.10 would

A scientist claims that only 65% of geese in his area fly south for the winter. He tags 55 random geese in the summer and finds that 17 of them do not fly south in the winter. If = .05, is the scientist's belief warranted?

State whether the null hypothesis should be rejected on the basis of the given P-value. P-value = 0.172, , one-tailed test

Using the z table, find the critical value (or values) for an = 0.03 two-tailed test.

Sandra Johnson, a researcher, believes her pulse rate will decrease with exercise. Her alternative hypothesis would contain an equal sign.

If the null hypothesis is not rejected when it is false, a type II error has occurred.