A poll conducted in 1974 asked 1004 people, \"During the past year, about how ma

Question

A poll conducted in 1974 asked 1004 people, "During the past year, about how many books, either hadove or paperback, did you read either all or part of the way through?" Results of the survey indicated that x·18.7 books and (a) Construct a 99% confidence interval for the mean number of books read either all or part of during the preceding year. Interpret the interval. (b) Compare these results to a recent survey of 1004 people. The results of the survey indicated that x = 12.6 books and s = 15.7 books. A 99% confidence interval for this survey is (11.32, 13.88). Were people reading more in 1974 than they are today? s 19.7 books. Click the icon to view the table of areas under the t-distribution. OU). (a) The 99% confidence interval for 1974 is (Use ascending order. Round to two decimal places as needed.)

Explanation / Answer

a) for std error of mean =std deviation/(n)1/2 =19.7/(1004)1/2 =0.6217

for 99% CI ; critical value of z =2.58

therefore 99% confidence interval for 1974 is =sample mean -/+z*Std error =17.10 ; 20.30

b) as above interval has values greater then maximum value of confidence interval of recent survey

therefore we have suffciient evidence that people were reading more in 1974

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