j_shreyans wrote:List X contains 8 integers. Is the standard deviation of the integers in list X equal to zero?
(1) The range of the integers in list X is 3.
(2) The average (arithmetic mean) of the integers in list X is 5.
SD=0 if NONE of the values DEVIATES from the mean.
Put another way:
SD=0 if ALL OF THE VALUES ARE THE SAME.
Question stem, rephrased:
Are all of the values the same?
Statement 1:
biggest - smallest = 3.
biggest = smallest + 3.
Since the biggest value is 3 greater than the smallest value, all of the values are NOT the same.
SUFFICIENT.
Statement 2:
Sum of the 8 integers = (number)(average) = 8*3 = 24.
Case 1: {3, 3, 3, 3, 3, 3, 3, 3}
In this case, all of the values are the same.
Case 2: {3, 3, 3, 3, 3, 3, 2, 4}
In this case, all of the values are NOT the same.
INSUFFICIENT.
The correct answer is
A.
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