Problem 14.3 The marketing manager of a large supermarket chain would like to determine the effect of shelf space on the sales of pet food. A random sample of 12 equal-sized stores is selected, with the following results: (see attachment for clearer tables) Store Shelf Space X (Feet) Weekly Sales Y (Hundreds of Dollars
1. Determine what would happen to your critical value (Z) if you were to change the level of significance (a) from .05 to .1 in a two tailed hypothesis test. 2. Why would the critical value change in the way you predict? 3. What does this suggest about the trade offs between Type 1 and Type II errors? Please give s
According to the historical data, the life expectancy in Argentina is equal to the life expectancy in Bolivia. A new study has been made to see whether this has changed. Records of 295 individuals from Argentina who died recently are selected at random. The 295 individuals lived an average of 74.8 years with a standard deviat
A study conducted by the research department of a pharmaceutical company claims that the annual spending (per person) for prescription drugs for allergy relief,u1 , is greater than or equal to the annual spending (per person) for non-prescription allergy relief medicine,u2 . A health insurance company conducted an independent st
An automobile assembly line operation has a scheduled mean completion time,u , of 12.6 minutes. The standard deviation of completion times is 1.8 minutes. It is claimed that, under new management, the mean completion time has decreased. To test this claim, a random sample of 48 completion times under new management was taken.
10. The manager of a computer software company wishes to study the number of hours senior executives spend at their desktop computers by type of industry. The manager selected a sample of five executives from each of three industries. At the .05 significance level, can she conclude there is a difference in the mean number of hou
A machine produces 3 inch nails. A sample of 10 nails was selected and the lengths determined: 2.89,2.95,3.00,3.05,2.99,2.96,3.10,3.06,3.00,3.12 Use the results to test Ho u=3 and Ha u not equal 3 at a=0.01. Give the computed test statistic and conclusion.
1. All Seasons Plumbing has two service trucks which frequently break down. If the probability the first truck is available is .75, the probability the second truck is available is .50, and the probability that both trucks are available is .30, what is the probability neither truck is available? 2. Textbook authors and publi
What are the steps in data analysis? Provide details of each step.
The manufacturer of Feel Better aspirin advertises that 60% of pediatricians recommend Feel Better for children under twelve. Safe and Sound, a rival manufacturer, surveyed 650 pediatricians and found that only 357 of them recommended Feel Better for children under twelve. Safe and Sound now claims that Feel Better's advertising
A researcher claims that the average age of a woman before he has her first child is now greater than it was in 1990. In 1990, that average age was 26.4 years. She obtains a random sample of 40 women who all recently gave birth to their first child, and calculates their mean age to be 27.1 years. From another recent study, she
Suppose a candidate running for sheriff claims that she will reduce the average speed of emergency response to less than 3o minutes. (30 minutes is thought to be the average response time with the current sheriff,) There are no past records so the actual standard deviation of such response times cannot be determined. Thanks to t
The NCAA requires colleges to report the graduation rates of their athletes. At one large university 70.7% of all students who entered between 1989 and 1991 graduated within 6 years. 95 of the 147 students who entered with athletic scholarships graduated. Consider these 95 as a sample of the athletes who will be admitted under p
What are some of the ethical issues we encounter in using hypothesis testing? How might we discover if a researcher has compromised ethics in reporting hypothesis testing results? When and how would we use hypothesis testing at our place of employment, or in politics?
The police chief of a large city claims that the mean age of bicycle thieves is 10.5 years. A sociologist who feels that this figure is too high takes a random sample of 28 cases of bicycle theft from the police chief's files, getting a mean of 8.9 years and a standard deviation of 3.2 years. Test the sociologist's hunch at the
Production process is considered to be under control if the machine parts it makes have a mean length of 35.50 mm with a standard deviation of 0.45 mm. Whether or not the process is under control is decided each morning by a quality control engineer who bases his decision on a random sample of size 36. Should he ask for an adjus
The college librarian believes that more than 60% of the books checked out by students were fictional material. In a random sample of 1000 students who checked books out in the last year, 650 checked out fictional material. What can one conclude about the librarian's hypothesis at a level of significance of .05?
In a speech to the Chamber of Commerce, a city councilman claims that in his city less than 15% of the adult male population is unemployed. A subsequent check taken by a newspaper reporter showed that among 300 adult males polled, 36 were unemployed. Is there sufficient evidence to support the councilman's claim at a level of si
A bowler who has averaged 196 pins in the past year is asked to experiment with a ball made of a new kind of material. If he rolls 25 games with the new ball, averaging 204 pins with a standard deviation of 24.9, can one conclude at a level of significance of .01 that the new ball has improved his game?
An instructor thinks that math majors can write and debug computer programs faster than business majors. A sample of 12 math majors took an average of 36 minutes to write a specific program and debug it; a sample of 18 business majors took an average of 39 minutes. The standard deviations were 4 minutes and 9 minutes, respective
A medical researcher wishes to see whether the pulse rates of smokers are higher than the pulse rates of nonsmokers. Samples of 100 smokers and 100 nonsmokers are selected. The results are shown here. Can the researcher conclude, at (confidence interval) =0.05 that smokers have higher pulse rates than nonsmokers?
1. Identify the null hypothesis and the alternative hypothesis. A researcher claims that 62% of voters favor gun control. 2. Assume that the data has a normal distribution and the number of observations is greater than fifty. Find the critical z value used to test a null hypothesis. alpha = 0.05 for a left-tailed test.
Chapter 12 problem 11 A machine is set to produce tennis balls so the mean bounce is 36 inches when the ball is dropped from a platform of a certain height The supervisor suspects that the mean bounce has changed and is less than 36 inches. As an experiment 42 balls were dropped from the platform and the mean height of the bo
Work through a t-test to compare the means of two groups of data. One possible example is to compare the tenure of females to the tenure of males. Select one of the quantitative variables from the DataSet (include all 288 cases) and perform a t-test to determine if the Population mean is equal to 5.0. Ensure that you begin by st
Research at the University of Toledo indicates that 50 percent of the students change their major area of study after their first year in a program. A random sample of 100 students in the College of Business revealed that 48 had changed their major area of study after their first year of the program. Has there been a significa
Lester Hollar is Vice President for Human Resources for a large manufacturing company. In recent years he has noticed an increase in absenteeism that he thinks is related to the general health of the employees. Four years ago, in an attempt to improve the situation, he began a fitness program in which employees exercise during
Team A did OK, once some adjustments were made to their offense and defense. However, Coach Mi is not convinced that his team is evenly matched to other teams in size. So he contacts Coach Lee of Team B to get the scoop on his team, and this is what he comes up with... Population Team A Team B Sample size n1 = 32 n2 =
The data set for our course is available via the following link DataSet and DataSet Key contains the following eight sections of data that will be used throughout our course: (1) Gender (2) Age (3) Department (4) Position (5) Tenure (6) Overall Job Satisfaction (7) Intrinsic Job Satisfaction - Satisfaction with the
A stockbroker at Critical Securities reported that the mean rate of return on a sample of 10 oil stocks was 12.6 percent with a standard deviation of 3.9 percent. The mean rate of return on a sample of 8 utility stocks was 10.9 percent with a standard deviation of 3.5 percent. At the .05 significance level, can we conclude tha
1) Flammability tests were conducted on children's sleepwear. The vertical semi restrained test was used, in which pieces of fabric were burned under controlled conditions. After the burning stopped, the length of the charred portion was measured and recorded. The same fabric samples were tested at five different laboratories