Formula Sheet BSTA 300 Final Comprehensive Exam Organization of Data Solution Correct Answer Key Question 1 In a market study for Target, a researcher found that 70% of customers are repeat customers. If 14 customers are selected at random, find the probability of getting. P = 0.7, q =1 – p = 0.3 n = 14 1. Exactly 9 of them are repeat customers P(X=9) = ଵସ ! ହ ! ଽ ! * (0.7) 9 (0.3) 0.3 = 0.196 2. At least 11 of them are repeat customers P(X>=11) = P(X=11) + P(X=12) + P(X=13) + P(X=14) =0.355 3. At most 12 of them are repeat customers P(X<=12) = P(X=0) + P(X=1) + P(X=2) + …..+ P(X=12) = 0.839 Question 2 Using computer software (Excel, or calculation website) find the following probabilities and z values to 5 decimal places 1. P(z< .12345)= 0.5491 2. Find z0 such that P(z>z0)=0.12345 z0 = 1.158 Question 3 Scores are obtained from the Law School Admission Test (LSAT) are normally distributed with a mean score of 650 and a standard deviation of 120. Mean = 650, SD = 120 1. If a test score is selected at random, find the probability that it is less than 700. z = (700 – 650)/120 = 0.4167 P(X<700) = P(z<0.4167) = 0.6616