Question

Compute the standard deviation of the following set of data to the nearest whole number: 8, 12, 15, 17, 18

a) 3
b) 4
c) 13
d) 14

Answer 1

we have that

set of data [8, 12, 15, 17, 18]

step 1
Find the mean
[8+ 12 + 15 + 17 + 18]/5-------> 70/5------> 14

step 2
for each number: subtract the Mean and square the result
(8-14)²----->36
(12-14)²----> 4
(15-14)²----> 1
(17-14)²----> 9
(18-14)²----> 16

step 3
work out the mean of those squared differences
[36+4+1+9+16]/5-----> 66/5-----> 13.2----> this value is called the "Variance"

step 4
Take the square root of that
standard desviation=√13.2-----> 3.63-------> 4

the answer is
4