Question

The standard deviation of a normallydistributed data set is 9. If 100 is 3 standarddeviations above the average value of the set,what is the value of the mean?(I really need help with this..)

Answer 1

Apply the formula:

`z=(x-\upsilon)/(\sigma)`

Where:

z= 3

x = value = 100

μ = mean = ?

σ= standard deviation = 9

Replacing:

`3=(100-\mu)/(9)`

Solve for the mean

3 *9 = 100- u

27 = 100-u

u = 100-27

u= 73

mean = 73