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!
