The incubation time for a breed of chicks is normally distributed with a mean of20days and standard deviation of approximately1day. Look at the figure below and answer the following questions. If1000eggs are being incubated, how many chicks do we expect will hatch in the following time periods? (Note: In this problem, let us agree to think of a single day or a succession of days as a continuous interval of time. Assume all eggs eventually hatch.)

(a) in18to22days chicks (b) in19to21days