70, 75, 80, 85, 90, 105, 105, 130, 130, 130
The list shown consists of the times, in seconds, that it took each of the 10 schoolchildren to run a distance of 400 meters. If the standard deviation of the 10 running times is 22.4 seconds, rounded to the nearest tenth of a second, how many of the 10 running times are more than 1 standard deviation below the mean of the 10 running teams?
A) 1
B) 2
C) 3
D) 4
E) 5
OA is B
Source: GMATPrep
The list shown consists of the times, in seconds, that it took each of the 10 schoolchildren to run a distance of 400 meters. If the standard deviation of the 10 running times is 22.4 seconds, rounded to the nearest tenth of a second, how many of the 10 running times are more than 1 standard deviation below the mean of the 10 running teams?
A) 1
B) 2
C) 3
D) 4
E) 5
OA is B
Source: GMATPrep
