110. 11364-!-item-!-187;#058&007646 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 这题不会啊，那个提亮的部分怎么理解呢
这题不会啊，那个提亮的部分怎么理解呢 | 
