Over the past three years, Shoprite Supermarket has observed the following distribution of modes of payment in the express lines: Cash (C) 41%, Cheques (Ck) 24%, Credit cards (D) 26%, and other (N) 9%. In an effort to make express checkout more efficient, Shoprite has just begun offering a discount for cash payment in the express checkout line. The table below presents the distribution of modes of payment for a sample of 500 express-line customers after the discount went into effect. Suppose you must test the hypothesis at 10% level of significance that the distribution of modes of payment in the express checkout line changed after the discount went into effect. Mode of payment Cash Checks Credit cards Other Number of customers 240 104 111 45 The expected frequencies for all mode of payment will be: a) 205, 120, 130 and 45 b) 120, 130, 115 and 45 Oc) 205, 102, 130 and 40 d) 130, 205, 45 and 115

The monthly incomes for 12 randomly selected people, each with a bachelor's degree in economics, are shown on the right. Complete parts (a) through (c) below. Assume the population is normally distributed. 4450.04 4596.08 4366.42 4455.64 4151.49 3727.22 4283.36 4527.36 4407.11 3946.91 4023.06 4221.57 (a) Find the sample mean. x = 4263.0 (Round to one decimal place as needed.) (b) Find the sample standard deviation. s = 260.0 (Round to one decimal place as needed.) (c) Construct a 90% confidence interval for the population mean μ. A 90% confidence interval for the population mean is (Round to one decimal place as needed.)

Split the Bill? Exercise 2.153 describes a study to compare the cost of restaurant meals when people pay individually versus splitting the bill as a group. In the experiment half of the people were told they would each be responsible for individual meal costs and the other half were told the cost would be split equally among the six people at the table. The data in SplitBill includes the cost of what each person ordered (in Israeli shekels) and the payment method (Individual or Split). Some summary statistics are provided in Table 6.20 and both distributions are reasonably bell-shaped. Use this information to test (at a 5% level) if there is evidence that the mean cost is higher when people split the bill. You may have done this test using randomizations in Exercise 4.118. Table6.20Cost of meals by payment type Payment  Sample size  Mean    Std. dev. Individual  24               37.29      12.54   Split           24             50.92      14.33

The American Association of Individual Investors (AAII) On-Line Discount Broker Survey polls members on their experiences with discount brokers. As part of the survey, members were asked to rate the quality of the speed of execution with their broker as well as provide an overall satisfaction rating for electronic trades. Possible responses (scores) were no opinion (0), unsatisfied (1), somewhat satisfied (2), satisfied (3), and very satisfied (4). For each broker summary scores were computed by calculating a weighted average of the scores provided by each respondent. Suppose a portion of the survey results follow. Brokerage Speed Satisfaction A 3.4 3.5 B 3.3 3.5 C 3.4 3.9 D 3.6 3.6 E 3.2 2.9 F 3.8 2.8 G 3.8 3.6 H 2.6 2.6 I 2.7 2.3 J 4.0 4.0 K 2.5 2.5 These ratings data on x = the quality of the speed of execution and y = overall satisfaction with electronic trades provided the estimated regression equation ŷ = 0.243 + 0.896x. At the 0.05 level of…