Question

1. We know that, in the population, the average memory span (number of items a person can recall) is 7, with a standard deviation of 2. We want to know if the herb gingko biloba can really enhance a person’s memory. We get a sample of 25 students and have them take the herb for one month and then test their memory span. What null hypothesis would we test? What is the alternative hypothesis?

2. We know that, in the population, the average child takes his or her first steps at the age of 12 months, with a standard deviation of 2 months. A psychologist wants to know if the children of professional athletes learn to walk at an earlier age. What null hypothesis would the psychologist test? What is the alternative hypothesis?

3. A 2011 survey reported that, in the population, college students received an average of 96 texts per day, with a standard deviation of 30 texts. You are interested in knowing if college professors receive more or fewer texts than their students. What null hypothesis would you test? What is the alternative hypothesis?

4. Research indicates that, in the U.S. population, the average age of onset of schizophrenia in men is 18 years old, with a standard deviation of 4.5 years. A clinical psychologist wants to know if the average age of onset is similar for men raised in a different culture. The psychologist gets medical reports from China to do this comparison. What null hypothesis would the researcher test? What is the alternative hypothesis?

Answer 1