Question

On a recent quiz, the class mean was 76 with a standard deviation of 2.7. Calculate the z-score (to 2 decimal places) for a person who received score of 82.
z score =

Is this unusual or not unusual?

Answer 1

given data

population mean   $\mu =76$

Population standard deviation $\sigma =2.7$

now have to calculate the Z score for

X=82

So from the formula of Z score

$Z=\frac{X-\mu }{\sigma }=\frac{82-76}{2.7}=2.22$

Since the value of Z lies between the range of the bell shape curve that is - 4 to 4 so it is not unusual value