A large corporation employs 25 comma 916 individuals. The average income several years ago for all employees was ​$73 comma 869 with a standard deviation of ​$19 comma 639. You are interested in comparing the incomes of​ today's employees with those of several years ago. A random sample of 100 employees of the corporation yields x overbarequals​$74 comma 724 and sequals​$18 comma 338. Complete parts a through d below.