Question

1. A salesperson has successes on 2 out of 10 cold calls. What is the probability of getting 3 successes in 9 cold calls?

2. If the probability of success on a cold call is .20, and 500 cold calls are made, what is the probability of less than 84.5 successes? (use normal distribution to approximate the binomial, so need mean = np and st.dev = sqrt(npq) )

3. In the past, the probability of success of a cold call has been .20. What is the probability that p will be more than .22 in a sample of 40 cold calls?

4. Find an interval estimate (with a 95% confidence coefficient) for the probability of a successful cold call (p), using a sample of 36 cold calls with p = .24.

5. A claim is made by a marketing manager that her salespeople have a success rate of at least .27. You want to test this claim with a .05 level of significance. You find p = .275 for n = 40.

6. Cold calls have different success rates depending on the salesperson. Find the 95% C.I. for the difference in success rates for 2 salespeople. Test to see if the diff. is significant at  = .05. Salesperson 1: n = 36 and p = .15 Salesperson 2: n = 49 and p = .40

7 A sample is taken of annual revenue (in 000s) for 8 individuals: 100 60 56 73 20 84 69 77 Find the mean, median, mode, range, variance and standard deviation for the sample.

8. Assuming revenues are normally distributed, find the probability that a randomly selected individual will have a revenue of $78 thousand or greater.

9. Find the sampling distribution for revenue where  = $15 thousand and  = $70 thousand and n = 50. What is the probability that a sample will have a mean between $75 and $90 thousand?

10. Find an interval estimate with 95% confidence for mean income of senior public accountants in Vancouver using a sample of 25 with x = $70 thousand. The total population of senior public accountants in Vancouver is 480 with a  of $15 thousand for income.

11. A public practice accountant claims that the mean annual revenue for small manufacturers is $250 thousand or greater. You wish to test this claim with a 5% level of significance. You collect a sample where n = 36 s = 30 thousand and x = 240 thousand. What is the probability of a Type II error for this test if the actual  = 240 and  = 30 thousand?

12. You want to compare the mean revenues of small service companies and small manufacturers. You decide to find an interval estimate for the difference between means with 95% confidence. You also want to test if the manufacturers make more than the service companies at a .01 level of significance. Use df = 23 Service: n = 22 x = 195 th s = 28 th Mnfctr: n = 14 x = 230 th s = 35 th.

Answer 1