Question

The data list shows the scores of ten students in Mr. Smith's math class. 61, 67, 81, 83, 87, 88, 89, 90, 98, 100 What is the standard deviation, to the nearest tenth, of the data if the scores represent a sample of Mr. Smith's students? _______a0 What is the standard deviation, to the nearest tenth, of the data if the scores represent the entire population of Mr. Smith's students? __________ a1

Answer 1

Sample standard deviation

Mean of data = 84.4

Calculate deviations from the mean = 23.4, 17.8, 3.4, 1.4, -2.6, -3.6, -4.6, -5.6, -13.6 and -15.6

Squaring these deviations; we get 547.56, 316.84, 11.56, 1.96, 6.76, 12.96, 21.15, 31.36, 184.96, 243.36

Adding these we get 1378.47

As its a sample Std Dev we divide by 10 - 1 = 9. For the popklation Std Dev we divide by the number of scores (10).

Std Deviation for sample = sqrt ( 1378.47 / 9) = 12.4 to nearest tenth (answer)

Population Std Dev = sqrt (1378.47 / 10) = 11.7 answer

Theres a lot of arithmetic there so hope i haven't slipped up anywhere!