The distribution of the heights of students in a school is symmetrical about
the mean height. It is found that 64% and 88% of the heights lie within one
and two standard deviations from the mean respectively. If the mean height
is 158cm and the standard deviation is 4 cm, find the percentage of
students with heights
a) Between 154 cm and 162 cm
b) between 150cm and 162 cm
c) less than 154 cm
d) more than 166 cm
F6 Statistics
2011-08-21 7:42 pm
回答 (1)
2011-08-21 10:10 pm
✔ 最佳答案
a) 154 cm = 158 cm - 4 cm = - 1 S.D.from mean162 cm = 158 cm + 4 cm = + 1 S.D. from mean
so percentage = 64%
b) 150 cm = 158 cm - 8 cm = - 2 S.D. from mean
So 150 cm - 162 cm = 88%/2 + 64%/2 = 44% + 32% = 76%
c) less than 154 cm = over 1 S.D. from mean = 50% - 64%/2 = 50% - 32% = 18%. (Note : Distribution is symmetrical about mean).
d) More than 166 cm = more than 2 S.D. from mean = 50% - 88%/2 = 50% - 44% = 6%.
收錄日期: 2021-04-25 22:38:56
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110821000051KK00302