2019 · Q61
Consider the following grouped frequency distribution:
Class: 0-10, Frequency: 8; Class: 10-20, Frequency: 12; Class: 20-30, Frequency: 10; Class: 30-40, Frequency: p; Class: 40-50, Frequency: 9.
If the mean of the above data is 25.2, then what is the value of p?
Elementary MathematicsStatistics
- A9
- B10
- C11
- D12
Explanation
Class marks 5, 15, 25, 35, 45 with frequencies 8, 12, 10, p, 9. Mean = (40+180+250+35p+405)/(39+p) = 25.2 ⇒ 875 + 35p = 982.8 + 25.2p ⇒ 9.8p = 107.8 ⇒ p = 11.