Q12 of 174 Page 577

The mean of 150 items was found to be 60. Later on, it was discovered that the values of two items were misread as 52 and 8 instead of 152 and 88 respectively. Find the correct mean.

Calculated mean of 150 items = 60


Incorrect sum of 150 items = 60×150 = 9000


Correct sum of 150 items = (incorrect sum) - (incorrect items) + (correct items)


= 9000 – (52 + 8) + (152 + 88)


= 9000 – 60 + 240


= 9240 – 60 = 9180


Correct mean =


So, correct mean is 61.2.


More from this chapter

All 174 →
10

The average weight of 10 oarsmen in a boat is increased by 1.5 kg when one of the crew who weights 58 kg is replaced by a new man. Find the weight of the new man.

 11

The mean of 8 numbers is 35. If a number is excluded then the mean is reduced by 3. Find the excluded number.

 13

The mean of 31 results is 60. If the mean of the first 16 results is 58 and that of the last 16 results is 62, find the 16th results.

 14

The mean of 11 numbers is 42. If the mean of the first 6 numbers is 37 and that of the last 6 numbers is 46, find the 6th number.