Question

the lenght of a species of fish is normally distributed with a mean of 24.3 inches and a standard deviation of 1.8 inches. What is the lenght that is exceeded by 30%of these fish

Answer 1

http://davidmlane.com/hyperstat/z_table.html

Answer 2

You will have to determine z-score (use a z-table with the information you are given), then use the z-score formula to find x (the length).

Z-score formula is this:

z = (x - mean)/sd
mean = 24.3
sd = 1.8

Once you find the z-score in the table, substitute the z-score and the data above into the formula and solve for x.