Multiple choice

The mean of 100 observations is 50. If the mean of the first 60 observations is 45, what is the mean of the remaining 40 observations?

  1. 55

  2. 57.5

  3. 60

  4. 62.5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total sum = 100 * 50 = 5000. Sum of first 60 = 60 * 45 = 2700. Remaining sum = 5000 - 2700 = 2300. Mean of remaining 40 = 2300 / 40 = 57.5.

AI explanation

The sum of all 100 observations is 100 multiplied by 50, which equals 5000. The sum of the first 60 observations is 60 multiplied by 45, giving a total of 2700. The sum of the remaining 40 observations is 5000 minus 2700, which is 2300. Dividing this by 40 gives a mean of 57.5.

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