The weights (to the nearest pound) of some boxes to be shipped are found to be:. Weight 65 68 69 70 71 72 90 95 frequency 1 2 5 8 7 3 2 2 Their mean weight is 72.97 pounds. What is the standard deviation of these weights? The standard deviation, to the nearest tenth, is a0.

A is the weight

B is the frequency

C is weight times frequency

D is mean minus weight

E is D raised to the 2nd power; variance

F is E times frequency; total variance

A B C D E F

65 1 65 7.97 63.47 63.47

68 2 136 4.97 24.70 49.40

69 5 345 3.97 15.76 78.80

70 8 560 2.97 8.82 70.57

71 7 497 1.97 3.88 27.17

72 3 216 0.97 0.94 2.82

90 2 180 17.03 290.02 580.04

95 2 190 22.03 485.32 970.64

30 2,189 1,842.91

2,189 / 30 = 72.97 mean

1,842.91 / 30 = 61.43 variance

√61.43 = 7.8377 or 7.84 standard deviation.