各位帅哥~美女们~问到题目~求解答~PREP中的MATH~！谢谢啦~

1木2头3人1 · 发表于 2011-5-25 22:20:20

the residents of town X participated in a survey to determine the number of hours per week each resident spent watching television. the distrabution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. the number of 6 hours, the number of Pat, a resident of town X, watched TV last week was between 1 and 2 standard diviations below the mean which of the following could be the number of hours that Pat watched TV last week.

nelly000 · 发表于 2011-5-26 00:04:12

在perp数学详解上找到的答案
差点中圈套
The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week?

(A) 30
(B) 20
(C) 18
(D) 12
(E) 6
------------------------------------------------------------------------------------------------------------------------------------
【答案】 D
【思路】平均數與標準差的概念
題目的數據: 平均數(mean) :21 hrs 標準差(standard deviation) : 6 hrs

由Pat 上星期看電視的時間在1~2個標準差之下可得知(between 1 and 2 standard deviations below the mean)，時間範圍應該坐落在9hrs~15hrs之間 ? 答案D 符合算出來的要求

1木2头3人1 · 发表于 2011-5-26 21:16:12

顶一下。。还是木有太懂啊。。。。。

1木2头3人1 · 发表于 2011-5-26 21:16:53

在perp数学详解上找到的答案
差点中圈套
The residents of Town X participated in a survey to determine the number of hours per week each resident spent watching television. The distribution of the results of the survey had a mean of 21 hours and a standard deviation of 6 hours. The number of hours that Pat, a resident of Town X, watched television last week was between 1 and 2 standard deviations below the mean. Which of the following could be the number of hours that Pat watched television last week?

(A) 30
(B) 20
(C) 18
(D) 12
(E) 6
------------------------------------------------------------------------------------------------------------------------------------
【答案】 D
【思路】平均數與標準差的概念
題目的數據: 平均數(mean) :21 hrs 標準差(standard deviation) : 6 hrs

由Pat 上星期看電視的時間在1~2個標準差之下可得知(between 1 and 2 standard deviations below the mean)，時間範圍應該坐落在9hrs~15hrs之間 ? 答案D 符合算出來的要求

-- by 会员 nelly000 (2011/5/26 0:04:12)

为什么是在9-15之间捏？

Avengeryzc · 发表于 2011-5-27 02:30:04

21-6=15
21-12=9
between 1 and 2 standard deviations below the mean

lastjuly · 发表于 2011-7-16 21:15:07

thx~

各位帅哥~美女们~问到题目~求解答~PREP中的MATH~！谢谢啦~

所属分类: GMAT考试

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