Multiple choice

The mean of 11 observations is 17.5. If an observation '15' is deleted, the mean of the remaining observations will be

  1. 16

  2. 17.75

  3. 17.5

  4. 17.25
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B Correct answer
Explanation

Total sum of 11 observations is 11 * 17.5 = 192.5. After removing 15, the new sum is 192.5 - 15 = 177.5. The new mean is 177.5 / 10 = 17.75.

AI explanation

First, find the total sum of the 11 observations by multiplying the mean by the number of observations, giving 17.5 times 11, which equals 192.5. When the observation valued at 15 is deleted, the new sum becomes 192.5 minus 15, resulting in 177.5. The new mean is this new sum divided by the remaining 10 observations, so 177.5 divided by 10 equals 17.75.

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