SOLUTION: : A set of 50 data values has a mean of 15 and a variance of 25. Find the standard score of a data value = 30.

Algebra ->  Probability-and-statistics -> SOLUTION: : A set of 50 data values has a mean of 15 and a variance of 25. Find the standard score of a data value = 30.      Log On


   

Question 551048: : A set of 50 data values has a mean of 15 and a variance of 25. Find the standard score of a data value = 30.
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!


z = %28xbar+-+mu%29%2F%28sigma%2Fsqrt%28n%29%29 where sigma = sqrt%28variance%29



and where when n > 30, we use the approximation s ≈ sigma.



So in this problem we use sigma ≈ s = sqrt%2825%29 = 5



z = %28xbar+-+mu%29%2F%28sigma%2Fsqrt%28n%29%29 = %2830-15%29%2F%285%2Fsqrt%2850%29%29 = 21.21320344.



That's an extremely high z-score but that's what you would 

expect since 30 is so extremely far above the mean of 15.



Edwin