请教一道模拟题

scarlett006

for a certain examination, a score of 58 was 2 standard deviation below the mean, a score of 98 was 3 standard deviation above the mean,what was the mean score of the exam.
A74  B 76     C78 D80 E82

题目看不懂，求

torresAing

58分低于均分两个标准差,98分高于均分三个标准差

58+2x=98-3x

x=8

均分=74

finnlijing

晕，没看清楚lz求什么，lz你是求安慰啊求翻译阿还是求解答阿