Multiple choice

The mean of 20 observations is 60. It was detected on rechecking that the value of 32 is wrongly copied as 62. The correct mean is:

  1. 59

  2. 59.60

  3. 58.5

  4. 58
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The original sum of 20 observations is 20 * 60 = 1200. The error is that 62 was added instead of 32, so the difference is 30. The correct sum is 1200 - 30 = 1170. The correct mean is 1170 / 20 = 58.5.

AI explanation

Using the formula for the sum of observations, the original sum is 20 multiplied by 60, which is 1200. Subtracting the incorrect value of 62 and adding the correct value of 32 gives a new sum of 1170. Dividing this new sum by 20 yields a correct mean of 58.5.

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