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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 z-scores and areas under the normal curve. for Jack z = 07 . 1 14 15 14 175 160- - =- =- x , when z = -1.07, area = .1423 for his sister 50 . 2 10 25 10 145 110- =- =- =- x , 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 7-year 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 variance = 112.1396 standard deviation =10.59 4) The Student Services office did a survey of 500 students in which they asked if the student is part-time or full-time. Another question asked whether the student was a transfer student. The results follow. Transfer Non-Transfer Row Totals Part-Time 100 110 210 Full-Time 170 120 290 Column Totals 270 230 500 a) If a student is selected at random (from this group of 500 students), find the probability that the student is a transfer student. P (Transfer) The total number of transfer students is 270.... View Full Document
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Exam 2
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