Multiple choice

If the average of first 12 numbers is 16.4, that of next 13 numbers is 12.4 and of the remaining 5 numbers is 20.8. Find the average of 30 numbers.

  1. 14.4

  2. 15.4

  3. 16.4

  4. 17.2

  5. 20.5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total sum = (12 * 16.4) + (13 * 12.4) + (5 * 20.8) = 196.8 + 161.2 + 104 = 462. Average = 462 / 30 = 15.4.

AI explanation

Using the weighted average method, multiply each group size by its average to find the sums. The sums are 12 times 16.4 which is 196.8, 13 times 12.4 which is 161.2, and 5 times 20.8 which is 104. The total sum is 462, and dividing this by the total of 30 numbers gives an average of 15.4.

Keep practicing — related questions