Answer:
The standard deviation of this sample is 7.438
Explanation:
We are given that Strength tests on four batches of concrete show them to fail at 81, 78, 86, and 95 ksi.
Data: 81, 78, 86, and 95
We are supposed to find standard deviation of this sample
Formula :[tex]\sqrt{\frac{(x-\bar{x})^2}{n-1}}[/tex]
n = 4
[tex]\bar x=\frac{81+78+86+95}{4}=85[/tex]
Substitute the values in the formula :
Standard deviation=[tex]\sqrt{\frac{(81-85)^2+(78-85)^2+(86-85)^2+(95-85)^2}{4-1}}[/tex]
Standard deviation=7.438
Hence The standard deviation of this sample is 7.438
