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In the July 29, 2001, issue of The Journal News (Hamilton, Ohio) Lynn Elber of t

ID: 2960035 • Letter: I

Question

In the July 29, 2001, issue of The Journal News (Hamilton, Ohio) Lynn Elber of the Associated Press reported on a study conducted by the Kaiser Family Foundation regarding parents’ use of television set V-chips for controlling their children’s TV viewing. The study asked parents who own TVs equipped with V-chips whether they use the devices to block programs with objectionable content.

a Suppose that we wish to use the study results to justify the claim that fewer than 20 percent of parents who own TV sets with V-chips use the devices. The study actually found that 17 percent of the parents polled used their V-chips.2 If the poll surveyed 1,000 parents, and if for the sake of argument we assume that 20 percent of parents who own V-chips actually use the devices, calculate the probability of observing a sample proportion of .17 or less. That is, calculate P.

b Based on the probability you computed in part a, would you conclude that fewer than 20 per- cent of parents who own TV sets equipped with V-chips actually use the devices? Explain.

Explanation / Answer

The mean of the distribution is 0.20 or 20% The standard deviation of the dist. is sqrt[0.20*0.80/1000] = 0.01265 z(0.17) = (0.17-0.20)/0.01265 = -0.03/0.01265 = -2.3715 P(p