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Unformatted text preview: X X X X X X X X X X X X X X X X X AP Statistics Solutions to Packet 9 X Sampling Distributions Sampling Distributions Sample Proportions Sample Means X X X X X X X X 2 HW #7 1 4, 9, 10 11 For each boldface number in Exercises 9.1 9.4, (a) state whether it is a parameter or a statistic and (b) use appropriate notation to describe each number; for example, p = 0.65. 9.1 MAKING BALL BEARINGS A carload lot of ball bearings has mean diameter 2.5003 centimeters (cm). This is within the specifications for acceptance of the lot by the purchaser. By chance, an inspector chooses 100 bearings from the lot that have mean diameter 2.5009 cm. Because this is outside the specified limits, the lot is mistakenly rejected. 2.5003 m = is a parameter; 2.5009 x = is a statistic. 9.2 UNEMPLOYMENT The Bureau of Labor Statistics last month interviewed 60,000 members of the U.S. labor force, of whom 7.2% were unemployed. 7.2% p = is a statistic. 9.3 TELEMARKETING A telemarketing firm in Los Angeles uses a device that dials residential telephone numbers in that city at random. Of the first 100 numbers dialed, 48% are unlisted. This is not surprising because 52% of all Los Angeles residential phones are unlisted. 48% p = is a statistic, 2% p = 5 is a parameter. 9.4 WELLFED RATS A researcher carries out a randomized comparative experiment with young rats to investigate the effects of a toxic compound in food. She feeds the control group a normal diet. The experimental group receives a diet with 2500 parts per million of the toxic material. After 8 weeks, the mean weight gain is 355 grams for the control group and 289 grams for the experimental group. 1 2 335 Both x and x = = 289 are statistics. 3 9.9 GUINEA PIGS Link the data of survival time for guinea pigs from another calculator. Consider these 72 animals to be the population of interest. Survival time (days) of guinea pigs in a medical experiment. 43 45 53 56 56 57 58 66 67 73 74 79 80 80 81 81 81 82 83 83 84 88 89 91 91 92 92 97 99 99 100 100 101 102 102 102 103 104 107 108 109 113 114 118 121 123 126 128 137 138 139 144 145 147 156 162 174 178 179 184 191 198 211 214 243 249 329 380 403 511 522 598 (a) Make a histogram of the 72 survival times. This is the population distribution. It is strongly skewed to the right. (b) Find the mean of the 72 survival times. This is the population mean . Mark on the xaxis of your histogram. For the 72 survival times, = 141.847 days. (c) Label the members of the population 01 to 72 and use Table B to choose a SRS of size n = 12. List your sample and find the mean x of your sample. All answers vary. ____ ____ ____ _____ ____ ____ ____ ____ ____ ____ ____ ____ x = _____ Mark the value of x with a point on the axis of your histogram. 4 (d) Repeat this three times....
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This note was uploaded on 03/01/2010 for the course STAT AP taught by Professor Kalliongis during the Spring '10 term at Kirkwood.
 Spring '10
 Kalliongis
 Statistics

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