How I can solve these question?

Question

how I calculate the standard deviation of the ages for the Last Six U.S. Presidents if we will want our final answer to be correct to 3 decimal places. So, we make sure we don't get any rounding error, we will do all calculations to 6 decimal places until the final answer.Round each answer to 6 decimal places. What is the mean age ( ¯¯¯ X ) of the Last Six Presidents? Round your answer to 6 decimal places.

Answer 1

Trump: 72

Obama: 57

GW Bush: 72

Clinton: 72

GHW Bush: 94

Reagan: 93

THe mean is 76 and 2/3

The standard deviation is 14.27819

PResident Age Dev Dev^2

Trump 72

Obama 57

GW Bush 72

CLinton 72

GHW Bush 94

REagan 93

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You need a 4 column table: President, Age, Dev, Dev^2, as shown above

You populate the first 2 columns with the data given.

mean = total of ages/6

for each age, the deviation is dev=age - mean. this is the 3rd column

the 4th column is the deviation squared or dev^2

you add up all of these columns.

the variance var= total of deviations squared / (6-1) = total of dev^2/5

the standard deviation is the square root of the variance.

President Age Stats.xls contains all of these calculations for you. I uploaded to the resource section.

Please read it