13.) Assuming that the sex of a person is determined at random, determine the probability that a family with three children has a.) Three girls b.) Exactly one boy c.) No girls d.) At least one girl e.) Two boys and a girl 15.) What is the probability of arriving at a traffic light when it is red if the red signal flashes for 30 seconds, the yellow signal for 5 seconds, and the green signal for 45 seconds? 17.) The mean annual starting salary of a new graduate in a certain profession is $30,000 with a standard deviation of $500. What is the probability (percentage) that the starting salary of a new graduate in this profession will be between $28,000 and $32,000? 18.) The average healing time of a certain type of incision is 240 hours, with standard deviation of 20 hours. What percentage of the people having this incision would heal in 8 days or less? Assume a normal distribution. 19.) The consumer price index (CPI) represents the change in prices of all goods and services. For each year from 1913 to 2006, the amount required to buy what $1 bought in 1913 is given by Where x is the number of years from 1900. a.) Find and explain what each means. b.) In what year will items costing $1 in 1913 cost $25, according to this model