The average of 37 numbers is 80. The average of the first 19 numbers is 75 and the average of the last 19 numbers is 84. If the 19th number is excluded, what is the average of the remaining numbers (approximate to one decimal place)?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 80.5.
Total sum of 37 numbers = 37 × 80 = 2960
Sum of first 19 numbers = 19 × 75 = 1425
Sum of last 19 numbers = 19 × 84 = 1596
19th number counted twice: 1425 + 1596 = 3021
So, 19th number = 3021 – 2960 = 61
New sum = 2960 – 61 = 2899
Average of 36 numbers = 2899 ÷ 36 ≈ 80.5