# J needed to make sure that the mean=100 & standard deviation =10. when J calculated these she found the actual standard deviation=8.4 and mean = 106.5. What does J have to do?

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### 1 Answer

The mean and standard deviation is estimated from values in a data set. J needs to ensure that the mean is 100 and the standard deviation is 10. But when these are calculated the mean is 106.5 and the standard deviation is 8.4.

J should first check that the formulas used by her are correct. Mean is determined by adding all the values in the data set and dividing the sum by the number of values in the data set. The standard deviation is determined by the formula `sqrt((1/N)*sum_(i)^N (x_i - mu)^2)` where `mu` is the mean and N is the number of values in the data set. If the mean and standard deviation have been estimated correctly, a change would have to be made in the values that are being used. There is no other way of changing the mean and standard deviation for the same values.

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