8.2 Point Estimator c Use these data to estimate the average weight of all the p

Question

8.2 Point Estimator c Use these data to estimate the average weight of all the participant in this race. 2. Suppose, in Prob. 1, that the data represented the weights of the top eight finishers in the marathon. Would you still be able to use these data to estimate the average weight of all the runners? Explain! To determine the average amount of money spent by university stu- dents on textbooks, a random sample of 10 students was chosen, and the students were questioned. If the amounts (to the nearest dollar) spent were 422, 146, 368, 52, 212, 454, 366, 711, 227, 680 what is your estimate of the average amount spent by all students at the university? 4. A random sample of nine praschoolers from a given neighborhood yielded the following data concerning the number of hours per day each one spent watching television: 3, 0, 5, 3.5, 1.5, 2, 3, 2.5, 2 Estimate the average number of hours per day spent watching televi- sion by preschoolers in that neighborhood. 5. A manufacturer of compact disk players wants to estimate the average lifetime of the lasers in its product. A random sample of 40 is chosen. If the sum of the lifetimes of these lasers is 6624 hours, what is the estimate of the average lifetime of a laser? 6. A proposed study for estimating the average cholesterol level of work- ing adults calls for a sample size of 1000. If we want to reduce the resulting standard error by a factor of 4, what sample size is

Explanation / Answer

3) The estimate would be (422 + 146 + 368 + 52 + 212 + 454 + 366 + 711 + 227 + 680)/10 = $363.8.

We do not exclude outliers as these could be valid data.

4) The average = ( 3 + 0 + 5 + 3.5 + 1.5 + 2 + 3 + 2.5 + 2)/9 = 22.5/9 = 3.5 hours

5) The average is 6624/40 = 165.6 hours

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