The mean incubation time of fertilized eggs is 21 days. Suppose the incubation times are approximately normally distributed with a standard deviation of 1 day.

(a) Determine the 20th percentile for incubation times.

(b) Determine the incubation times that make up the middle 39% of fertilized eggs.

(a) The 20th percentile for incubation times is ____days.

(Round to the nearest whole number as needed.)

(b) The incubation times that make up the middle 39% of fertilized eggs are____ to ____Days.

(Round to the nearest whole number as needed. Use ascending order.)