9.11 The formula used to compute a large-sample confidence interval for p is p⁄

6 sz critical valuedÎp⁄

s1 2p⁄

d n

What is the appropriate z critical value for each of the following confidence levels?

a. 95%

d. 80%

b. 90%

e. 85%

c. 99%

9.12 The use of the interval p⁄

6 sz critical valuedÎp⁄

s1 2p⁄

d n

requires a large sample. For each of the following combinations of n and p⁄

, indicate whether the sample size is large enough for use of this interval to be appropriate.

a. n 5 50 and p⁄

5 .30

b. n 5 50 and p⁄

5 .05

c. n 5 15 and p⁄

5 .45

d. n 5 100 and p⁄

5 .01

e. n 5 100 and p⁄

5 .70

f. n 5 40 and p⁄

5 .25 g. n 5 60 and p⁄ 5 .25 h. n 5 80 and p⁄

5 .10