A company surveyed 25 consumers who shop online and the company has collected data on the change in shopping volume measured in dollars following an advertising campaign. They found that the average increase in spending to be 26$ with a sample standard deviation of 9$.

The company expected the advertising campaign to effect a change in average spending of more than 30$.

Test the company's expectation by using the critical value method at 5% significance level.

You need to

(a)state null and alternative hypotheses

(b)show proper statistic for the test and steps of derivation

(c)make decisions for the test