sd

[gmatnmein2010]

For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean. What was the mean score for the examination?
(A) 74
(B) 76
(C) 78
(D) 80
(E) 82

[shashank.ism]

For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean. What was the mean score for the examination?
(A) 74
(B) 76
(C) 78
(D) 80
(E) 82

Let M be the mean & S = 1 standard deviation

M + 3S = 98 ---------(i)
M - 2S = 58 ---------(ii)

solving above 2 equations , we get:
S = 8
--> M = 2S+58 = 74

[thephoenix]

x - 2sd = 58
x + 3sd = 98

SD = 8 and Mean (x) = 74

[komal]

For a certain examination, a score of 58 was 2 standard deviations below the mean, and a score of 98 was 3 standard deviations above the mean. What was the mean score for the examination?
(A) 74
(B) 76
(C) 78
(D) 80
(E) 82

x - 2sd = 58
x + 3sd = 98

SD = 8 and Mean (x) = 74 in A.

[sadullaevd]

2sd=58

3sd =98

to find one sd=> (98-58)/5 =8

mean - 2sd = 58

mean 74

hope it helps