Given that the median of the numbers 15,8,11,21,32,5,25,7 is m. If 15 is replaced by 7, then the new median is n. Find the difference between m and n.
3.5
For an even count of numbers, the median is the mean of the two middle values after arranging the numbers in order.
Arranged: 5, 7, 8, 11, 15, 21, 25, 32. The 4th and 5th values are 11 and 15, so \(m = \frac{11 + 15}{2} = 13\).
Replacing 15 by 7 and arranging: 5, 7, 7, 8, 11, 21, 25, 32. The 4th and 5th values are 8 and 11, so \(n = \frac{8 + 11}{2} = 9.5\).
Difference = 13 – 9.5 = 3.5.
Check: in the new list three values (5, 7, 7) lie below 8 and three (21, 25, 32) lie above 11, so 8 and 11 are indeed the two middle values.
Hence, 3.5.
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Age | Frequency |
15 – 25 | 2 |
25 – 35 | 4 |
35 – 45 | 6 |
45 – 55 | 5 |
55 - 65 | 3 |
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