the mean of 50 observations was 36 . it was found later an observation 48 was wrongly taken as 23 . the corrected new means is :
"solution correct sum = ( 36 × 50 + 48 - 23 ) = 1525 . ∴ correct mean = 1825 / 50 = 36.5 answer c"
divide(add(multiply(36, 50), subtract(subtract(50, const_2), 23)), 50)