Multiple choice

Mean of 10 items was found to be 15. On verification, it was found that an item 21 was miscopied as 12. The correct mean is

  1. 15.9

  2. 14.1

  3. 24

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Original sum = 10 * 15 = 150. Error: 12 was used instead of 21. Difference = 21 - 12 = 9. Correct sum = 150 + 9 = 159. Correct mean = 159 / 10 = 15.9.

AI explanation

The initially calculated total sum of the 10 items is 10 multiplied by 15, which equals 150. The correct item is 21, but it was recorded as 12, so the correct total sum increases by the difference: 150 + (21 - 12) = 159. The correct mean is the correct total sum divided by the number of items: 159 divided by 10 equals 15.9.

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