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  1. The mean marks of 30 students in a class is 58.5. Later on, it was found that 75 was wrongly recorded as 57. Find the correct mean.
    1. 57.4
    2. 57.5
    3. 58.9
    4. 59.1
Correct Option: D

Correct mean = ( sum of total marks - 57 + 75 ) / 30
= ( 30 x 58.5 - 57 + 75 ) / 30
= (1755 + 18 ) / 30
= 59.1


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