Which of the following situations calls for a hypothesis test about a population mean?

a. According to the Center for Disease Control (CDC), roughly 21.5% of all U. S. highschool seniors in 2002 have used marijuana. A sociologist suspects that the rate among African-American high school seniors is lower.

b. A recent study estimated that 20% of all college students in the United States smoke. The head of Health Services at Goodheart University suspects that the proportion of smokers may be lower there.

c. A certain prescription allergy medicine is suppose to contain an average of 245 parts per million (ppm) of active ingredient. The manufacturer wants to check whether the mean concentration in a large shipment of pills is 245 ppm or not.

d. A report on the College Board website stated that in 2003 males scored generally higher than females on the SAT exam. An educational researcher wants to check whether this is true in her school district.

Step-by-step explanation:

Hypothesis test about a population mean is done to evaluate two exclusive statements about a population in order to determine which is best supported by the sample data.

From the situations given, the correct options are

b. A recent study estimated that 20% of all college students in the United States smoke. The head of Health Services at Goodheart University suspects that the proportion of smokers may be lower there. This would require taking a sample and determining the probability of success.

c. A certain prescription allergy medicine is suppose to contain an average of 245 parts per million (ppm) of active ingredient. The manufacturer wants to check whether the mean concentration in a large shipment of pills is 245 ppm or not.

d. A report on the College Board website stated that in 2003 males scored generally higher than females on the SAT exam. An educational researcher wants to check whether this is true in her school district.