Question

) Salesw oman Sally used her previous years' sales records to construct the following probability distribution for the random variable X. The random variable X represents the number of sales per day Corresponding to each value of X is its probability. X P(x) 0 0.25 1 0.30 2 0.15 3 0.10 4 0.10 5 0.10 a) What is the probability that between 2 and 4 sales, inclusixe, will be made on any given day? b) Compute the mean or expected value for the number of sales per day. (Do not round your answer.) a college freshman takes a Math class the first semester is 0.75. The probability that a freshman takes both a Science class and a Math class the first semester is 0.6. 6.) The probability that a college freshman takes a Science class the first semester is 0.55. The probability that Find the probability that the student takes either a Science class or a Math class or both in the first semester. a) b) Find the probability that the student takes neither Science nor Math in the first semester.

Answer 1

5)a) P(2 < X < 4) = P(X = 2) + P(X = 3) + P(X = 4)

                            = 0.15 + 0.10 + 0.10 = 0.35

b) Mean = 0 * 0.25 + 1 * 0.30 + 2 * 0.15 + 3 * 0.10 + 4 * 0.10 + 5 * 0.10 = 1.8

6)a) P(either Science or math) = P(science) + P(math) - P(science and math)

                                        = 0.55 + 0.75 - 0.6 = 0.7

b) P(neither science nor math) = 1 - P(either science or math)

                                                  = 1 - 0.7 = 0.3