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Mat 157/BusAd 221 Homework 3 Due 6/22/12 by 5pm Name___________________________________ 1) Determine whether the distribution represents a probability distribution. If not, identify any requirements that are not satisfied. x 3 6 9 12 15 P(x) -0.3 0.5 0.1 0.3 0.4 2) The random variable X represents the number of credit cards that adults have along with the corresponding probabilities. Find the expected value of X. X 0 1 2 3 4 1) 2) P(X=x) 0.07 0.68 0.21 0.03 0.01 3) Assume that male and female births are equally likely and that the birth of any child does not affect the probability of the gender of any other children. Find the probability of exactly two boys in three births. 1 3) 4) The probability that an individual is left-handed is 0.11. In a class of 40 students, what is the probability of finding two left-handers? 4) 5) Assume 5) that male and female births are equally likely and that the birth of any child does not affect the probability of the gender of any other children. Suppose that 800 couples each have a baby; find the mean and standard deviation for the number of girls in the 800 babies. 6) Find the area of the indicated region under the standard normal curve. A) 0.0968 7) Find B) 0.9032 C) 0.0823 D) 0.4032 the area of the indicated region under the standard normal curve. A) 0.309 B) 1.309 C) 0.6562 2 6) D) 0.3438 7) 8) Find the area of the indicated region under the standard normal curve. A) 0.9177 B) 0.9032 C) 0.0823 D) 0.0968 9) An airline knows from experience that the distribution of the number of suitcases that get lost each week on a certain route is approximately normal with µ = 15.5 and σ = 3.6. What is the probability that during a given week the airline will lose more than 20 suitcases? A) 0.3944 B) 0.1056 C) 0.4040 that the salaries of elementary school teachers in the United States are normally distributed with a mean of $32,000 and a standard deviation of $3000. If a teacher is selected at random, find the probability that he or she makes more than $36,000. B) 0.1056 C) 0.4040 3 9) D) 0.8944 10) Assume A) 0.0918 8) D) 0.9082 10)