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Going nuts The UR Nuts Company sells Deluxe and Premium nut mixes, both of which

contain only cashews, Brazil nuts, almonds, and peanuts. The Premium nuts are much

more expensive than the Deluxe nuts. A consumer group suspects that the two nut mixes

are really the same. To find out, the group took separate random samples of pounds of

each nut mix and recorded the weights of each type of nut in the sample. Here are the

data:

Explain why we can’t use a chi-square test to determine whether these two distributions

differ significantly.

Short Answer

Expert verified

We cannot perform a chi-square test, since the chi-square test requires the observational tallies rather than weights.

Step by step solution

01

Given information

We have been given the weights of different types of nuts in two mixes.

02

Explanation

We note that the given table contains weights, whereas we have not been given the observational checks for each cell. We will at that point not perform a chi-square test, because the chi-square test requires the observational checks rather than weights. That is, the variable is quantitative (numerical) rather than categorical and the chi-square test requires categorical factors.

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Most popular questions from this chapter

Is your random number generator working? Use your calculator’s RandInt function to generate 200 digits from 0 to 9 and store them in a list.

a. State appropriate hypotheses for a chi-square test for goodness of fit to determine whether your calculator’s random number generator gives each digit an equal chance of being generated.

b. Carry out a test at the α=0.05 significance level. Hint: To obtain the observed

counts, make a histogram of the list containing the 200 random digits, and use the trace feature to see how many of each digit were generated. You may have to adjust your window to go from 0.5to9.5 with an increment of 1

c. Assuming that a student’s calculator is working properly, what is the probability that the student will make a Type I error in part (b)?

d. Suppose that 25 students in an AP® Statistics class independently do this exercise for homework and that all of their calculators are working properly. Find the probability that at least one of them makes a Type I error.

Video games (1.1) To determine if there is a relationship between age and playing video games, the Pew Research Center asked randomly selected adults for their age and if they “ever play video games on a computer, TV, game console, or portable device like a cell phone.”3 Here is a two-way table summarizing the results of the study:

a. Construct a segmented bar graph to display the relationship between age group and response to the question about video games.

b. Describe the association shown in the segmented bar graph in part (a).

A random sample of traffic tickets given to motorists in a large city is examined. The tickets are classified according to the race or ethnicity of the driver. The results are summarized in the following table.

The proportion of this city's population in each of the racial/ethnic categories listed is as follows.

We wish to test H0: The racial/ethnic distribution of traffic tickets in the city is the same as the racial/ethnic distribution of the city's population.

We compute the value of the χ2test statistic to be 6.57. Assuming that the conditions for inference are met, which of the following is the correct P-value?

a. Greater than0.20

b. Between 0.10and0.20

c. Between 0.05and0.10

d. Between 0.01and0.05

e. Less than0.01

Roulette Refer to Exercise 2.

a. Confirm that the expected counts are large enough to use a chi-square distribution to calculate the P-value. What degrees of freedom should you use?

b. Use Table C to find the P-value. Then use your calculator’s χ2 cdf command.

c. What conclusion would you draw about whether or not the roulette wheel is operating correctly?

Treating ulcers Gastric freezing was once a recommended treatment for ulcers in the upper intestine. Use of gastric freezing stopped after experiments showed it had no effect. One randomized comparative experiment found that28of the 82gastric-freezing patients improved, while 30of the 78patients in the placebo group improved. We can test the hypothesis of “no difference” in the effectiveness of the treatments in two ways: with a two-sample z test or with a chi-square test.

a. State appropriate hypotheses for a chi-square test.

b. Here is Minitab output for a chi-square test. Interpret the P-value. What conclusion would you draw?

c. Here is Minitab output for a two-sample z test. Explain how these results are consistent with the test in part (a).

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