The average of 22 numbers is 37.5. The average of first 12 numbers is 40.6 and that of the last 12 numbers is 35.4. If 11th and 12th numbers are excluded, then what is the average of the remaining numbers?
-
$37.8$
-
$37.4$
-
$36.4$
-
$36.9$
D
Correct answer
Explanation
Total sum of 22 numbers = 22 × 37.5 = 825. Sum of first 12 = 12 × 40.6 = 487.2. Sum of last 12 = 12 × 35.4 = 424.8. Since 11th and 12th are counted in both sets, their sum = 487.2 + 424.8 - 825 = 87. Sum of remaining 20 numbers = 825 - 87 = 738. Average = 738/20 = 36.9