For a certain exam,a score of 60 was 2 standard deviations below mean and a score of 100 was 3 standard deviations above mean.What was the mean score for the exam?  Choose the correct choice from the following options.
A) 74	B) 76	C) 78	D) 80	E) 82

Rationale: "mean - 2 sd = 60 mean + 3 sd = 100 by solving above we get , sd ( absolute value ) = 8 mean = 76 ans . b"
Answer: B