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2. A poll found that 38% ofarandom sample of 1012 Am believe in ghosts. (ch 16)

ID: 3340090 • Letter: 2

Question

2. A poll found that 38% ofarandom sample of 1012 Am believe in ghosts. (ch 16) erican adults said that they a. Find the margin of error for this poll if we want 90% confidence in our estimate of American adults who believe in ghosts. b. Find the "90% confidence interval" for the true mean proportion of American adult sand interpret it. If we want to be 99% confident, will the margin oferror be larger or smaller? Find that margin of error. ler margins of error involve greater or less confidence in the interval?

Explanation / Answer

Here, we are asked to the part c)

If we computed the 90% confidence interval for the true mean proportion in part b) , clearly as the confidence itnerval width and that the margin of error increases as the confidence level increases. Therefore for 99% confidence the margin of error would be larger than that for 90% confidence interval.

d) In general greater the confidence level, greater would be the value of z to compute the margin of error and therefore greater would be the margin of error. Therefore in general smaller margin of error incolves less confidence in the interval.