200 students scored a mean of 500 with a sum of squares of 1000 on the SAT-Verbal test.What is variance estimate?
A)2.242
B)2.236
C)5.000
D)5.025

Question

Quizplus · Accepted Answer

Variance estimate formula is:
s^2 = (SS - (ΣX^2 / N)) / (N-1)

SS is the sum of squares = 1000
ΣX^2 is the sum of the squared deviations from the mean = (500 * 500)*200 = 50,000,000/200 = 250,000
N is the number of students = 200

s^2 = (SS - (ΣX^2 / N)) / (N-1)
s^2 = (1000 - (250,000 / 200)) / (200-1)
s^2 = 5.025

Therefore, the answer is D) 5.025

200 Students Scored a Mean of 500 with a Sum