Exam (elaborations) MATH 221 FINAL EXAM REVIEW(Version 2) QUESTIONS WITH ANSWERS: DEVRY UNIVERSITY

1) Jack weighs 160 pounds and his sister weighs 110 pounds. If the mean weight for men his age is 175 with a standard deviation of 14 pounds and the mean weight for women is 145 with a standard deviation of 10 pounds, determine whose weight is closer to "average." Write your answer in terms of z­scores and areas under the normal curve. for Jack z = 1.07 14 15 14 160 175 ≈ − − = − = − σ x µ , when z = ­1.07, area = .1423 for his sister 2.50 10 25 10 110 145 = − − = − = − σ x µ , when z = ­2.50, area = .0062 Jack is closer to average, but he is still in the lower 14%, while his sister is in the bottom less than 1% of the population. 2) Explain the difference between a population and a sample. In which if these is it important to distinguish between the two in order to use the correct formula? mean; median; mode; range; quartiles; variance; standard deviation. A sample is a subset of a population. A population consists of every member of a particular group of interest. The variance and the standard deviation require that we know whether we have a sample or a population. 3) The following numbers represent the weights in pounds of six 7­year old children in Mrs. Jones' 2nd grade class. {25, 60, 51, 47, 49, 45} Find the mean; median; mode; range; quartiles; variance; standard deviation. mean = 46.166.... median = 48 mode does not exist range = 35 Q1 = 45 Q2 = median = 48 Q3 = 51