Use z-scores.
Formula:
z = (x - mean)/sd
Use a z-table to find a z-score equating to 30%. Use 3 for the mean and .25 for the standard deviation. Solve the formula for x.
I hope this will help get you started.
The retail price of 12-pack soda can be characterized as having a normal distribution with a mean of 3 dollars and a standard deviation of .25. Below what price do you find 30 % of all 12 packs?
1 answer