2014 · Q95
The mean of the following distribution is 18.
Class interval: 11-13 (frequency 3), 13-15 (6), 15-17 (9), 17-19 (13), 19-21 (f), 21-23 (5), 23-25 (4).
What is the value of f?
Elementary MathematicsStatistics
- A8
- B9
- C10
- D11
Explanation
Using class marks 12,14,...,24: (36+84+144+234+20f+110+96)/(40+f) = 18 gives f = 8.