Find the range variance and standard deviation for each of t

Find the range, variance, and standard deviation for each of the two samples, then compare the two sets of results. When investigating times required for drive-through service, the following results (in seconds) were obtained (show work)
Restaurant A: 120, 67, 89, 97, 124, 68, 72, 96
Restaurant B: 115, 126, 49, 56, 98, 76, 78, 95

Solution

Set 1: 120, 67, 89, 97, 124, 68, 72, 96
Range : maximum - minimum = 124-67 = 57

Number of cases 7
To find the mean, add all of the observations and divide by 8
Mean = (120 + 67 + 89 + 97 + 124 + 68 + 72 + 96)/8 = 91.625
Squared deviations
(120-91.625)^2 = 805.140625
(67-91.625)^2 = 606.390625
(89-91.625)^2 = 6.890625
(97-91.625)^2 = 28.890625
(124-91.625)^2 = 1048.140625
(68-91.625)^2 = 558.140625
(72-91.625)^2 = 385.140625
(96-91.625)^2 = 19.140625
Add the squared deviations and divide by 7
Variance = (805.140625 +606.390625+6.890625 +28.890625+1048.140625+558.140625 +385.140625+19.140625)/7
Variance = 493.9821
Standard deviation = sqrt(variance) = 22.2257

Set 2: 115, 126, 49, 56, 98, 76, 78, 95

Range : 126 - 49 = 77

Number of cases 8
To find the mean, add all of the observations and divide by 8
Mean 86.625
Standard deviation = sqrt(variance) = 26.98

The range and standard deviation for restaurant A is smaller than that of restaurant A. This shows there is more variation in restaurant B with respect to times required for drive through service than in A.