Question

the mean and standar deviation of set of 100 Observation were worked out as 40 and 5 respectively by a computer who by mistake to the value of 50 in place of 40 for one observation. recalculate the correct mean and variance

Answer 1

Answer on Question #73864 – Math – Statistics and Probability

Question

The mean and standard deviation of set of 100 observations were worked out as 40 and 5 respectively by a computer who by mistake to the value of 50 in place of 40 for one observation. Recalculate the correct mean and variance.

Solution

Firstly, we get that $40 * 100 = 4000$, after that we change 50 to 40, hence the correct sum should be $4000 - 50 + 40 = 3990$. The correct mean is $3990 / 100 = 39.9$. The variance won't change because the sample size is the same and a shift won't affect the variance.

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