21.38 Will they charge more? A bank wonders whether omitting the annual credit card fee for customers who charge at least $2500 in a year will increase the amount charged on its credit cards. The bank makes this offer to an SRS of 200 of its credit card customers. It then compares how much these customers charge this year with the amount that they charged last year. The mean increase in the sample is $346, and the standard deviation is $112. Give a 99% confidence interval for the mean amount charges would have increased if this benefit had been extended to all such customers.

21.38 Will they charge more? A bank wonders whether omitting the annual credit card fee for customers who charge at least $2500 in a year will increase the amount charged on its credit cards. The bank makes this offer to an SRS of 200 of its credit card customers. It then compares how much these customers charge this year with the amount that they charged last year. The mean increase in the sample is $346, and the standard deviation is $112. Give a 99% confidence interval for the mean amount charges would have increased if this benefit had been extended to all such customers.

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

The average cost of an IRS Form 1040 tax filing at Thetis Tax Service is $157.00. Assuming a normal distribution, if 70 percent of the filings cost less than $171.00, what is the standard deviation?
A banker finds that the number of times people use automated-teller machines (ATMs) in a year are normally distributed with a mean of 40.0 and a standard deviation of 11.2 (based on data from Maritz Marketing Research, Inc.). Find the proportion of customers who use ATMs between 20 and 60 times. Use four decimal places for your answer
The mean monthly rent for a one-bedroom apartment without a doorman in Manhattan is $2663. Assume the standard deviation is $506. A real estate firm samples 106 apartments. Find the 9 percentile of the sample mean. Round the answer to at least two decimal places.
In a metal fabrication process, metal rods are produced that have an average length of 20.5meters with a standard deviation of 2.3 meters. A quality control specialist collects a randomsample of 30 rods and measures their lengths.a. Describe the sampling distribution of the sample mean by naming the model andtelling its mean and standard deviation.b. Suppose the resulting sample mean is 19.5 meters. Do you think that this sampleresult is unusually small? Explain.
a small company is looking to see if they have reached their goal of $30.20, in saving per family. To see if goal was met their goal they randomly surveyed 50 of their 1000 customers, found that they saved average of $32.12 with a standard deviation of $4.83. Have they attained their saving goal.
High-rent district: The mean monthly rent for a one-bedroom apartment without a doorman in Manhattan is $2550. Assume the standard deviation is $485. A real estate firm samples 85 apartments. Use Excel.
A company wants to assess the average time it takes for customers to complete a particular task on their website. They collect the following data from a sample of 10 customers: 5, 6, 7, 8, 9, 10, 10, 11, 12, 13 minutes. Calculate the sample mean and standard deviation for this data.
the mean charge for satellite television for a sample of households was $87.50 per month, with a standard deviation of $14.50 per month. Estimate the percent of satellite television charges between $73.00 and $102.00
An air condition company will spend an average of 64 minutes with a standard deviation of 19 minutes on a service call. Based on this, and assuming a normal distribution, 5% of service calls will take more than how much time to complete? Approximately 66.29 minutes O Approximately 32.75 minutes O Approximately 39.41 minutes O Approximately 95.25 minutes O Approximately 77.23 minutes
A criminologist rode along with patrol officers for several weeks and recorded the number of minutes police officers spent interviewing witness at a variety of crime scenes. Using data collected on a group of 35 patrol officers, she observes an average interviewing time of 307 minutes. Assume that the population standard deviation a is estimated to be 83 minutes. What is the point estimate for the population mean, p? minutes Submit Question
What percent of people paid over $17,100?
The SAT and ACT college entrance exam are taken by thousands of students each year. The mathematics portions of each of these exams produce scores that are approximately normally distributed. In recent years, SAT mathematics exam scores have averaged 480 with standard deviation 100. The average and standard deviation for ACT mathematics scores are 18 and 6, respectively. a. An engineering school sets 550 as the minimum SAT math score for new students. What percentage of students will score below 550 in a typical year? b. What score should the engineering school set as a comparable standard on the ACT math test?