I dont understand how to find the answers using just 112 and 2656

Given the sample data. x: 21, 19, 15, 30, 27 (a) Find the range. (Enter an exact number.) (b) Verify that Ex = 112 and Ex2 = 2,656. (For each answer, enter an exact number.) Ex = 112 Ex2 = 2656 (c) Use the results of part (b) and appropriate computation formulas to compute the sample variance s and sample standard deviation s. (For each answer, enter a number. Round your answers to two decimal places.) $2 = x x = (d) Use the defining formulas to compute the sample variance s and sample standard deviation s. (For each answer, enter a number. Round your answers to two decimal places.) = (e) Suppose the given data comprise the entire population of all x values. Compute the population variance of and population standard deviation o. (For each answer, enter a number. Round your answers to two decimal places.)