Question

The average marks of candidates in an aptituste test

was 128.5with a standard deviation of 8.2
Three scores extracted from the test are
148,102, 152, what is the average of the
extracted scores that are extreme values
fouthers (out the coutlier)
​

Answer 1

102

Explanation:

We must calculate the value of z for each value and then compare each one and thus manage to see what is an outlier, we know that z is equal to:

z = (x - m) / sd

where x is the value to evaluate, m the mean and sd the standard deviation. Now we have to:

For x = 148:

z = (148 - 128.5) /8.2

z = 2.37

For x = 102:

z = (102 - 128.5) /8.2

z = -3.23

For x = 152:

z = (152 - 128.5) /8.2

z = 2.86

The value of this is generally between -3.09 and 3.09, so when x is 102, it goes out of range of the value of z, which means that this is the outlier.