c. Example 1: A two-sample z-test for the difference between means: An advertising executive claims that there is a difference in the mean household income for credit card holders of Visa Gold and of Gold MasterCard. The results of a random survey of 100 customers from each group are shown below. The two samples are independent. Do the results support the executive's claim? Use a = 0.05. Visa Gold Gold MasterCard X, =$ 60,900 X, =$ 64,300 s, = $12,000 S, = $15,000 n, =100 n, =100