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A problem about median!!
Given the following data:(distribution:frequency)
2:r(unknown)
3:12
4:20
5:10
The median of the distribution is 4, find the number of possible values of r.
(Show all the steps and explain clearly pls~)
2 個解答
- ?Lv 79 年前最愛解答
The no. of data is r + 12 + 20 + 10 = 42 + r
The median is the (42 + r)/2 number, which is 4
So, (42 + r)/2 > r + 12
42 + r > 2r + 24
r < 18
However, when r = 17, (42 + r)/2 = 29.5, this means that the median is the average of 3 and 4, which is 3.5.
So, the no. of possible values of r is 16
- 9 年前
r=0, median = 4
r=1, median = 4
...
r=17, median = 4
r=18, median = (3+4)/2 = 3.5
so, r = 0 ... 17, total 18 possible values
