Multiple choice

The average of 20 numbers is 12. The average of the first 12 numbers is 11 and that of the next 7 numbers is 10. The last number is

  1. 40

  2. 38

  3. 48

  4. 50

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sum of 20 numbers = 20 * 12 = 240. Sum of first 12 = 12 * 11 = 132. Sum of next 7 = 7 * 10 = 70. Sum of 19 numbers = 132 + 70 = 202. The last number = 240 - 202 = 38.

AI explanation

The total sum of the 20 numbers is 20 times 12, which equals 240. The sum of the first 12 numbers is 12 times 11, or 132, and the sum of the next 7 numbers is 7 times 10, or 70. The combined sum of these 19 numbers is 132 plus 70, giving 202. The last number is found by subtracting this combined sum from the overall total of 240. The last number is 38.