A marketing researcher for a phone company surveys 200 people and finds that the

Question

A marketing researcher for a phone company surveys 200 people and finds that the proportion of clients who are likely to switch providers when their contract expires is 0.15 a) What is the estimated standard deviation of the sampling distribution of the proportion? b) If she wants to reduce the estimated standard deviation by half, how large of a sample would she need? a) The estimated standard deviation of the sampling distribution of the proportion is (Round to four decimal places as needed.) b) She will need a sample of (Type a whole number.) Enter your answer in each of the answer boxes.

Explanation / Answer

here proportion=p=0.15 and sample size=200

(a) standard deviation(sd) of proportion p=sqrt(p(1-p)/n)=sqrt(0.15*(1-0.15)/200)=0.0252

(b) since sd is inversly proprotional to sqrt(n), so if we want to reduce the sd by half( 1/2) , so we need the sample size 4 times more i.e. 4*200=800

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.