The mean and standard deviation of 10 observations are 20 and 8 respectively. Later on, it was observed that one observation was recorded as 50 instead of 40. Then the correct variance is:
- (A)14
- (B)13✓ Correct
- (C)12
- (D)11
Answer: (B)
Solution
Original mean , so . Corrected sum = , so corrected mean .
Original variance , so , giving .
Corrected .
Corrected variance = .
Original variance , so , giving .
Corrected .
Corrected variance = .
JEE Main · 2023 · 15 Apr 2023 · Shift 1 · Single correct option