19. A recent study of the hourly wages of maintenance crews for major airlines showed that the mean hourly salary was $16.50,
with a standard deviation of $3.50. If we select a crew member at random, what is the probability the crew member earns:
a. Between $16.50 and $20.00 per hour?
b. More than $20.00 per hour?
c. Less than $15.00 per hour?
23. A cola-dispensing machine is set to dispense on average 225 mL of cola per cup. The standard deviation is 10 ml. The
distribution amounts dispensed follows a normal distribution.
a. What is the probability that the machine will dispense between 235 mL and 250 mL of cola?
b. What is the probability that the machine will dispense 250 mL of cola or more?
c. What is the probability that the machine will dispense between 205 mL and 250 mL of cola?
26. A survey reported that the mean starting salary for college graduates in the spring of 2011 was $33 176. Assume that the
distribution of starting salaries follows the normal distribution with a standard deviation of $3500. What percent of the
graduates have starting salaries:
a. Between $30 000 and $38 000?
b. More than $42 000?
c. Between $38 000 and $42 000?