Conventional home smoke alarms have too often failed to awaken sleeping children--they are remarkably resistant to being awakened by sound, even in the daytime! Researchers are studying the possibility that a personalized "voice" smoke alarm would be more effective than mere sound. The idea is that a recording of the mother's voice calling the child's name may be an improvement over existing systems.
a) The researchers would like to estimate π to within 0.05 with 95% confidence. Past experience has shown that conventional alarms are effective about 0.58 of the time. If this is accepted as a reasonable initial estimate of π, what sample size should they use for their study?
b) Suppose the researchers felt that the original study, done with children of parents working in a single hospital, was different enough so that their results (p = 0.58) should not be relied upon. In a few sentences, explain how your procedure for choosing a samples size would differ from your solution in part (a). (Do NOT recalculate a new estimate of the necessary sample size!)

Question

Conventional home smoke alarms have too often failed to awaken sleeping children--they are remarkably resistant to being awakened by sound, even in the daytime! Researchers are studying the possibility that a personalized "voice" smoke alarm would be more effective than mere sound. The idea is that a recording of the mother's voice calling the child's name may be an improvement over existing systems. 
a) The researchers would like to estimate π to within 0.05 with 95% confidence. Past experience has shown that conventional alarms are effective about 0.58 of the time. If this is accepted as a reasonable initial estimate of π, what sample size should they use for their study? 
b) Suppose the researchers felt that the original study, done with children of parents working in a single hospital, was different enough so that their results (p = 0.58) should not be relied upon. In a few sentences, explain how your procedure for choosing a samples size would differ from your solution in part (a). (Do NOT recalculate a new estimate of the necessary sample size!)

Quizplus · Accepted Answer

The Answer is a) a) = 374.3255 Thus, a sample of at least 375 children will be needed. b) If no price estimate of the population proportion is available, using p = 0.50 in the formula for n above would provide a sufficient sample size.

a) = 374.3255 Thus, a sample of at least 375 children will be needed. b) If no price estimate of the population proportion is available, using p = 0.50 in the formula for n above would provide a sufficient sample size.

= 374.3255 Thus, a sample of at least 375 children will be needed.
b) If no price estimate of the population proportion is available, using p = 0.50 in the formula for n above would provide a sufficient sample size.

Conventional Home Smoke Alarms Have Too Often Failed to Awaken