I really need this

Question

A normal distribution has a mean of 0.40 and standard deviation of 0.028. What percentage of observations will live between 0.372 and 0.428?

Answer 1

Compute the z-score for 0.428 then for 0.372.

z = (x - μ) / σ

where x = 0.428 or 0.372, μ = the mean = 0.40, and σ = the standard deviation = 0.028. Once you have the z scores for both values, look up the corresponding percentiles in a z-score table (look in your book or find one on the internet). Subtract the percentile of 0.372 from the percentile for 0.428 to get the answer.