Question

A researcher knew that before cell phones, a person made on average 2.8 calls per day. He believes that the number of calls made per day today is higher. He selects a random sample of 33 individuals who use a cell phone and asks them to keep track of the number of calls that they made on a certain day. The mean was 3.1. At a=0.10, is there enough evidence to support the researcher's claim? The standard deviation for the population found by a previous study is 0.9. Assume that the variable is normally distributed. Use the p-value method with a graphing calculator.

Answer 1