作者minimumi (米尼)
看板GMAT
标题[计量] PrepT2-PS-Q166
时间Mon Nov 5 11:30:29 2007
166.
70, 75, 80, 85, 90, 105, 105, 130, 130, 130
The list shown consists of the times, in seconds, that it took each of 10
schoolchildren to run a distance of 400 meters. If the standard deviation
of the 10 running times is 22.4 seconds, rounded to the nearest tenth of a
second, how many of the 10 running times are more than 1 standard deviation
below the mean of the 10 running times?
(A) One
(B) Two
(C) Three
(D) Four
(E) Five
想请问一下这题该怎麽解~
谢谢!
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1F：推 vanillatown:答案是B吗? 11/05 12:54
2F：推 reznor:Mean:100, 1 standard deviation lower=100-22.4=77.6 11/05 15:01
3F：→ reznor:所以两人 11/05 15:02
4F：推 minimumi:了解了～谢谢! 11/05 16:47