Telephone Calls 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...

Telephone Calls 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 30 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 2.9. At =α0.01, is there enough evidence to support the researcher's claim? The standard deviation for the population found by a previous study is 0.7. Assume that the variable is normally distributed. Use the critical value method with tables.