2條MATHS 題阿喂 2條MATHS 題阿喂

3a.
mean = sum of the data / number of data
mean = (45 + 45 + 50 + 55 + 60 + 65 + 65 + 75 + 75 + 75)/10 = 61

3b.
mode = the number appears most often
mode = 75

3c.
median = after the rearrangement, the middle one
median = (60 + 65) / 2 = 62.5

4a.
(x + 45 + 47 + 49 + 46 + 43 + 52 + 50) /8 = 47.5
x = 48

4b.
rearrangement = {43, 45, 46, 47, 48, 49, 50, 52}
↑ ↑
median = (47 + 48) / 2 = 47.5

**
if the number of data is odd, choose (N+1) / 2 -th term
if the number of data is even, choose N/2 + (N+2) /2

2007-08-13 23:50:08 補充：
another pagea.no. of girls like playing piano = 40 x 135 / 360 = 15b.% of girls who like playing the guzheng among the girls = 45 / (45 18) x 100% = 71.43%c.% of stud who like playing violin= 72 / 360 x 40% 25% x 60%= 23%