Omar recorded the number of hours he worked each week for a year. below is a random sample that he took from his data. 13, 17, 9, 21 what is the standard deviation for the data?

standard deviation=4.47

Step-by-step explanation:

We have to find the standard deviation of the data set:

13   17    9  21

Now we calculate the mean of the data .

We know that mean is the average of the data values and is calculated as:

Now we find the difference of each data point from the mean as:

Deviation:

13-15=-2

17-15=2

9-15=-6

21-15=6

Now we have to square the above deviations we obtain:

4   4   36   36

now we calculate the mean of the above sets:

now standard deviation is the positive square root of variance

so, standard deviation=√(20)=4.47

the least common denominatore of 7 and 2 is 9

step-by-step explanation:

7+2=9

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step-by-step explanation: