Multiple choice

The average of eight numbers is $38.4$ and the average of seven of them is $39.2$. What is the eighth number?

  1. $0.8$
  2. $32.8$
  3. $34.8$
  4. $33.8$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Sum of 8 numbers = 8 * 38.4 = 307.2. Sum of 7 numbers = 7 * 39.2 = 274.4. The eighth number = 307.2 - 274.4 = 32.8.

AI explanation

The total sum of all eight numbers is 8 times 38.4 = 307.2. The sum of the seven numbers is 7 times 39.2 = 274.4. The eighth number is the difference between these sums, which is 307.2 minus 274.4 = 32.8.

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