Answer:

Step-by-step explanation:
Given: 76,45,64,80,92
Required: Determine the standard deviation
We start by calculating the mean

Where x-> 76,45,64,80,92 and n = 5



Subtract Mean (71.4) from each of the given data

Determine the absolute value of the above result

Square Individual Result

Calculate the mean of the above result to give the variance


Hence, Variance = 255.298
Standard Deviation is calculated by 



Answer:
4 x 63 = 252
Step-by-step explanation:
There's 4 groups of 63 students.
52.22 - 39.58 = 12.64
12.64 / 4 = $ 3.16 per shirt
Exact form: -square root 2/2 (I don't have a square root symbol)
Decimal form: -0.70710678