There Are Several Published Tests of Suggestibility $\Sigma$ X = 684 $\Sigma$

There are several published tests of suggestibility. Suppose that the population mean for a particular test is 20. An advertising class, taught by a hard-nosed skeptic, had just finished the term. A psychologist wanted to determine the effect of the course on gullibility and she chose the suggestibility test as a way to measure gullibility. The higher the score, the greater the gullibility. The following statistics were produced. Use a 95 percent confidence interval to analyze the data. Write a conclusion about the effect of the class.N = 36 $\Sigma$ X = 684 $\Sigma$ X² = 13, 136