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Chapter 1: Q T1.7. (page 79)
Forty students took a statistics examination having a maximum of points. The score distribution is given in the following stem-and-leaf plot:
The third quartile of the score distribution is equal to
The correct option is (b)
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Shopping spree A marketing consultant observed 50 consecutive shoppers at a supermarket. One variable of interest was how much each shopper spent in the store. Here are the data (in dollars), arranged in
increasing order:
(a) Round each amount to the nearest dollar. Then make a stem plot using tens of dollars as the stems and dollars as the leaves.
(b) Make another stem plot of the data by splitting stems. Which of the plots shows the shape of the distribution better?
(c) Write a few sentences describing the amount of money spent by shoppers at this supermarket.
The National Survey of Adolescent Health interviewed several thousand teens (grades 7 to 12). One question asked was "What do you think are the chances you will be married in the next ten years?" Here is a two-way table of the responses by gender: Your percent from the previous exercise is part of-
(a) the marginal distribution of gender.
(b) the marginal distribution of opinion about marriage.
(c) the conditional distribution of gender among adolescents with a given opinion.
(d) the conditional distribution of opinion among adolescents of a given gender.
(e) the conditional distribution of 鈥淎lmost certain鈥� among females.
Choose a graph What type of graph or graphs would you plan to make in a study of each of the following issues at your school? Explain your choices.
(a) Which radio stations are most popular with students?
(b) How many hours per week do students study?
(c) How many calories do students consume per day?
An experiment was conducted to investigate the effect of a new weed killer to prevent weed growth in onion crops. Two chemicals were used: the standard weed killer (C) and the new chemical (W). Both chemicals were tested at high and low concentrations on a total of 50 test plots. The percent of weeds that grew in each plot was recorded. Here are some boxplots of the results. Which of the following is not a correct statement about the results of this experiment?
(a) At both high and low concentrations, the new chemical (W) gives better weed control than the standard weed killer (C).
(b) Fewer weeds grew at higher concentrations of both chemicals.
(c) The results for the standard weed killer are less variable than those for the new chemical.
(d) High and low concentrations of either chemical have approximately the same effects on weed growth.
(e) Some of the results for the low concentration of weed killer W show fewer weeds growing than some of the results for the high concentrate
Smoking by students and parents Here is data from a survey conducted at eight high schools on smoking among students and their parents:
(a)How many students are described in the two-way table? What per cent of these students smoke?
(b) Give the marginal distribution of parents鈥� smoking behaviour, both in counts and in percentages.
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