91影视

The data values are $7,7,9,9$

Calculate the average first.

Step 2: Determine each score's standard deviation.

Step 3: Calculate the square root of each standard deviation.

Step 4: Add up the squares to get the total.

Step 5: Work out how much of a difference there is.

Step 6: Determine the square root of the variance.

The number of values in the sample size is: $n=4$

The mean is calculated by dividing the total number of values by the sample size: $\overline{X}=\frac{7+7+9+9}{4}=\frac{32}{4}=8$

If $Xi$are the data values, then $Xi-\overline{X}$are the deviations,${(Xi-\overline{X})}^2$

the squared deviations:

The variance is calculated by dividing the sum of the squared deviations by n-1: ${s_x}^2=\frac{1+1+1+1}{4-1}=\frac{4}{3}$

The square root of the variance is the standard deviation: $s_x=\sqrt{\frac{4}{3}}鈮�1.1547$

Hence, $1.1547$ is the standard deviation.

This suggests that the difference between a typical amount of sleep and the mean should be $1.1547$ hours. Hence, $1.1547$ is the expected distance.

No, because the students were not chosen at random and the sample was a convenience sample, the answer is no. The results of a convenience sample cannot be applied to the entire population. The students that arrive earliest to class, for example, are likely to require the least amount of sleep.