Multiple choice

The mean of $100$ observations is $50$. If one of the observations which was $50$ is replaced by$ 150$, the resulting mean will be :

  1. $50.5$
  2. $51$
  3. $51.5$
  4. $52$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Original sum = 100 * 50 = 5000. New sum = 5000 - 50 + 150 = 5100. New mean = 5100 / 100 = 51.

AI explanation

The original total sum of the 100 observations is 100 * 50 = 5000. Replacing an observation of 50 with 150 increases the total sum by 100, making the new sum 5100. The new mean is the new sum divided by 100, which is 5100 / 100 = 51.

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