Erin O'Brien, Director of Consumer Credit with Auckland First Bank (AFB), has implemented a

"fast feedback' to keep her informed of the default rate on personal loans at AFB member

banks. On each Friday, the default rate is calculated for a sample of 500 personal loans. Last

Friday's sample contained 30 defaulted loans. The 90% confidence interval for the population

proportion is

Select one:

O a. 0.039 to 0.081

O b. 0.028 to 0.060

O c. 0.046 to 0.074

Dd. 0.043 to 0.077

The z-value associated with a two-sided 82% confidence interval is

Select one:

O a. 1.34

O b. 1.75

O c. 1.41

O d. 0.46

Life tests performed on a sample of 13 batteries of a new model indicated: (1) an average life

of 75 months, and (2) a standard deviation of 5 months. Other battery models, produced by

similar processes, have normally distributed life spans. The 98% confidence interval for the

population mean life of the new model is

Select one:

O a. 61.60 to 88.41

O b. 63.37 to 86.63

O c. 71.77 to 78.23

O d. 71.28 to 78.72

When estimating a sample size necessary to estimate p, and there is no approximation for the

value of p available, the value of _

should be used as an estimate of p in the formula.

Select one:

O a. 1.96

O b. 0.10

O c. 0.50

O d. 0.40

A bank officer wishes to estimate the average total deposits per customer at the bank. She

would like the estimate to be within $100 of the actual average with 90% confidence. She

assumes the standard deviation for this should be $800. How large should the sample be?

Select one:

O a. 51

O b. 17,318

O c. 174

O d. 246

Nick Petritis, Operations Manager with the Palmerston North Trust Bank, is evaluating the

service level provided to walk-in customers. Accordingly, his staff recorded the waiting times

for 64 randomly selected walk-in customers and determined that their mean waiting time was

15 minutes. Assume that the population standard deviation is 4 minutes. The 88% confidence

interval for the population mean of waiting times is _

Select one:

O a. 14.11 to 15.89

O b. 14.33 to 15.67

O c. 8.80 to 21.20

O d. 10.30 to 19.70

Cameron Sinclair, Information Services Manager with Global Financial Service (GFS), is

studying employee use of GFS email for non-business communications. A random sample of

200 email messages was selected. Thirty of the messages were not business related. The

point estimate for this population proportion is

Select one:

O a. 0.300

O b. 0.182

O c. 0.150

O d. 0.667

Cameron Sinclair, Information Services Manager with Global Financial Service (GFS), is

studying employee use of GFS email for non-business communications. A random sample of

200 email messages was selected. Thirty of the messages were not business related. The

90% confidence interval for the population proportion is

Select one:

O a. 0.091 to 0.209

O b. 0.108 to 0.192

O c. 0.153 to 0.247

O d. 0.145 to 0.255

Suppose a researcher wants to conduct a study to estimate the population mean. He plans to

use a 95% level of confidence to estimate the mean, and the population standard deviation is

approximately 34. The researcher wants the error to be no more than 4. The sample size

should be at least

Select one:

O a. 278

O b. 7

O c. 196

O d. 1110

A researcher wants to estimate the proportion of a population which possess a given

characteristic. A random sample of size 250 is taken and 40% of the sample possess the

characteristic. The 95% confidence interval to estimate the population proportion is

Select one:

O a. 0.35 to 0.45

O b. 0.34 to 0.46

O c. 0.39 to 0.41

O d. 0.37 to 0.43