The mean of 11 numbers is 35. If the mean of the first six numbers is 32 and that of the last six numbers is 37, then the 6th number is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 29
The first six numbers and the last six numbers together cover all 11 numbers, but the 6th number is counted in both groups. So the two group totals added together exceed the total of all 11 numbers by the 6th number.
Total of all 11 numbers \(=11\times35=385\)
Total of the first six \(=6\times32=192\)
Total of the last six \(=6\times37=222\)
6th number \(=192+222-385=29\)