standard deviation

Question

The mean daily snowfall amounts for whoville in Dec is 25 in and the standard deviation is 1.5 in assuming the data is normally distributed how many days would you expect the daily snowfall to be greater than 26.5 in

Answer 1

Obtain a z-score table:

http://www.utdallas.edu/dept/abp/zscoretable.pdf

 

z = (X - μ) / σ, X = data, μ = mean, σ = standard deviation

 

z = (26.5 - 25) / 1.5

z = 1.5 / 1.5

z = 1

 

For a z-score of 1, 84.13% is below. Therefore 15.87% lie above.