2025 · Q99
Consider the distribution with median 24: Marks less than 10, 20, 30, 40, 50 have frequencies 5, 30, 30+k, 48+k, 55+k. What is k? [The options could not be verified]
Elementary MathematicsStatistics
- A5
- B10
- C15
- D20
Explanation
Cumulative frequencies 5, 30, 30+k, 48+k, 55+k give class frequencies 5, 25, k, 18, 7 (N=55+k). Median 24 in class 20-30: 20+[(N/2-30)/k]*10=24 gives (55+k)/2-30=0.4k, so k=25. But 25 is NOT among the options (5, 10, 15, 20) - the options appear misprinted. (Q100's mean 24.625 is computed with k=25.) The key is taken from the published coaching key (PW, CDS 2 2025 Set A: C, i.e. 15). Note: key disputed - independent verification inconclusive.