Cesarean birth study. In Exercise 4.73 (p. 240), you learned that 75% of all births in a region occur by Cesarean section each year. In a random sample of 1,000 births this year, let x be the number that occur by Cesarean section. LO8

a. Find the mean of x.

b. Find the standard deviation of x.

c. Find the z-score for the value x = 810.

d. Find the approximate probability that the number of Cesarean sections in a sample of 1,000 births is less than or equal to 810.