The mean of a set of seven numbers is 81. If one of the numbers is discarded, the mean of the remaining numbers is 78. The value of discarded number is 98         (b)  99              (c)  100        (d)  101

Explanation

Given:

Mean of `7` numbers `= 81`

Total `= 7 xx 81 = 567`

By discarding one number, the mean of the remaining 6 numbers `= 78`

Total `= 6xx78 = 468`

Discarded number `= 567 - 468 = 99`

Option (b) is correct answer