The mean of 50 observations was 36. It was found later that an observation 48 was wrongly taken as 23. The corrected (new) mean is
Options:
A . 36.1
B . 35.2
C . 39.1
D . 36.5
Answer: Option D Answer: (d)The sum of 50 observations = 50 × 36 = 1800 The correct mean = ${1800 - 23 + 48}/50$= $1825/50$ = 36.5Aliter : Using Rule 26,The correct average will be = m +${\text"(a-b)"}/ \text"n"$.Here, n = 50, m = 36 a = 48, b = 23 Correct Average = m + ${\text"(a - b)"}/ \text"n"n$ = 36 +${(48 – 23)}/50$= 36 +$25/50$ = 36.5
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