In a study, people were observed for about 10 seconds in public places, such as...

In a study, people were observed for about 10 seconds in public places, such as malls and restaurants, to

determine whether they smiled during the randomly chosen 10-second interval. The researchers observed

600 people who were aged 20 years or younger, and 47% of these people smiled. The researchers also

observed 975 people who were aged 21 years or older, and 32% of these people smiled. (Treat this data

as if it were two simple random samples.)

a) Fill in the following table.

	Age Range
	0–20	21+
Number who smiled ()
Total number in sample (
Proportion who smiled ()

b) Determine and interpret the 95% confidence interval estimate of the difference between the population

proportions.

c) What does this suggest about how often people in these age groups smile? Does one group smile

significantly more often than the other? If so, which one?

Expert Solution

orchestra answered 1 year ago

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