The mean of the marks scored by 50 students was found to be 39. Later on it was discovered that a score of 43 was misread as 23. The correct mean is (a) 38.6 (b) 39.4 (c) 39.8 (d) 39.2
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Solution
ANSWER: (b) 39.4 Mean of the marks scored by 50 students = 39 Sum of the marks scored by 50 students = 39×50=1950 Correct sum = (1950 + 43 - 23) = 1970 ∴Mean=197050=39.4