Standard deviation

Question

The lightest 20% of apples get made into apple sauce (again with a mean of 243 grams and standard deviation of 23 grams). What is the minimum weight to avoid being turned into applesauce? Round to the nearest whole number.

Answer 1

Look on a normal distribution table (or use calculator) to find what value of z gives an area to the left of .2 (or .8 for area to right)

From this you can solve for x such that (x-avg)/sd = z