In a computer store chain, all PC tablets are sold with the option of a discount coupon for some application packages. Some of them are low-priced tablets, and some are the upmarket models. To learn the buying habits of customers and find out how to encourage application sales, the seller decides to select a random sample of 407 customers and to ask if they have also purchased the discount coupon, with the following results: CI.5. A manufacturer is concerned about the variability of the levels of impurity contained in consignments of raw material from a supplier. A random sample of 15 consignments showed a standard deviation of 2.36 in the concentration of impurity levels. Assume normality. Is it possible to conclude at 10% significance level (90% confidence level) that the people buying upmarket tablets are also more willing to purchase option coupons?