Multiple choice

The average weight of 20 persons was found to be 89.4 kg. After some time, it was observed that one person's weight was misread as 78 kg instead of 87 kg. The correct average weight (in kg) would be

  1. 88.95

  2. 89.25

  3. 89.55

  4. 89.85
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sum of weights = 20 * 89.4 = 1788. The error was 87 - 78 = 9 kg. Correct sum = 1788 + 9 = 1797. Correct average = 1797 / 20 = 89.85.

AI explanation

Using the correct average formula, the total correction in the sum is 87 minus 78, which equals 9 kg. This 9 kg increase is distributed across 20 persons, giving an average increase of 9 divided by 20, or 0.45 kg. Adding 0.45 kg to the initial average of 89.4 kg gives the correct average of 89.85 kg.

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