The average of 33 numbers is 74. The average of the first 17 numbers is 72.8 and that of the last 17 numbers is 77.2. If the 17th number is excluded, then what will be the average of the remaining numbers (correct to one decimal place) ?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 ie 72.9.
(a1 + ......a33) + a17 = 17(72.8 + 77.2)
(33 × 74) + a17 = 17 × 150
a17 = 2550 - 2442 = 108
If a17 is excluded,
New average = 74 - (34/32)
= 74 - (17/16)
= 72.9