Question

What is the standard deviation of the following data set rounded to the nearest tenth? 56 ,78 ,123 , 34, 67, 91, 20

Answer 1

Answer:

The standard deviation of the following data set is 32.2

Step-by-step explanation:

step 1

Find the mean

we have

$[56,78,123,34,67,9,20]$

Sum the data and divided by the number of elements

$[56+78+123+34+67+91+20]/7=469/7=67$

step 2

For each number: subtract the Mean and square the result

$[(56-67)^{2},(78-67)^{2},(123-67)^{2},(34-67)^{2},(67-67)^{2},(91-67)^{2},(20-67)^{2}]$

$[121,121,3,136,1,089,0,576,2,209]$

step 3

Work out the mean of those squared differences

$[121+121+3,136+1,089+0+576+2,209]/7=1,036$

This value is called the "Variance"    

step 4

Take the square root of the variance

$standard\ deviation=\sqrt{1,036}=32.2$