# Question: A teller at a drive up window at a bank had

A teller at a drive-up window at a bank had the following service times (in minutes) for 20 randomly selected customers:

a. Determine the mean of each sample.

b. If the process parameters are unknown, estimate its mean and standard deviation.

c. Estimate the mean and standard deviation of the sampling distribution.

d. What would three-sigma control limits for the process be? What alpha risk would they provide?

e. What alpha risk would control limits of 4.14 and 4.86 provide?

f. Using limits of 4.14 and 4.86, are any sample means beyond the control limits? If so, which one(s)?

g. Construct control charts for means and ranges using Table. Are any samples beyond the control limits? If so, which one(s)?

h. Explain why the control limits are different for means in parts d and g.

i. If the process has a known mean of 4.4 and a known standard deviation of .18, what would three-sigma control limits be for a mean chart? Are any sample means beyond the control limits? If so, which one(s)?

a. Determine the mean of each sample.

b. If the process parameters are unknown, estimate its mean and standard deviation.

c. Estimate the mean and standard deviation of the sampling distribution.

d. What would three-sigma control limits for the process be? What alpha risk would they provide?

e. What alpha risk would control limits of 4.14 and 4.86 provide?

f. Using limits of 4.14 and 4.86, are any sample means beyond the control limits? If so, which one(s)?

g. Construct control charts for means and ranges using Table. Are any samples beyond the control limits? If so, which one(s)?

h. Explain why the control limits are different for means in parts d and g.

i. If the process has a known mean of 4.4 and a known standard deviation of .18, what would three-sigma control limits be for a mean chart? Are any sample means beyond the control limits? If so, which one(s)?

## Answer to relevant Questions

A process that produces computer chips has a mean of .04 defective chip and a standard deviation of .003 chip. The allowable variation is from .03 to .05 defective. a. Compute the capability index for the process. b. Is the ...As part of an insurance company’s training program, participants learn how to conduct an analysis of clients’ insurability. The goal is to have participants achieve a time in the range of 30 to 45 minutes. Test results ...What is aggregate planning? What is its purpose?A manager would like to know the total cost of a chase strategy that matches the forecast below using a steady regular production rate of 200 units a month, a maximum of 20 units per month of overtime, and subcontracting as ...Refer to Solved Problem 1. Suppose another option is to use part- time workers to assist during seasonal peaks. The cost per unit, including hiring and training, is $ 11. The output rate is 10 units per worker per period for ...Post your question