MHR 231 Midterm 2 | Course Paper

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True or False: A worker earns $15 per hour at a plant in China and is told that only

2.5% of all workers make a higher wage. If the wage is assumed to be normally

distributed and the standard deviation of wage rates is $5 per hour, the average wage for

the plant is $7.50 per hour.

TABLE 8-8

The president of a university would like to estimate the proportion of the student

population that owns a personal computer. In a sample of 500 students, 417 own a

personal computer.

True or False: Referring to Table 8-8, the parameter of interest is the mean number of

students in the population who own a personal computer.

True or False: Problems may arise when statistically unsophisticated users who do not

understand the assumptions behind the statistical procedures or their limitations are

misled by results obtained from computer software.

True or False: TABLE 17-10

Given below are results from the regression analysis where the dependent variable is

the number of weeks a worker is unemployed due to a layoff (Unemploy) and the

independent variables are the age of the worker (Age), the number of years of education

received (Edu), the number of years at the previous job (Job Yr), a dummy variable for

marital status (Married: 1 = married, 0 = otherwise), a dummy variable for head of

household (Head: 1 = yes, 0 = no) and a dummy variable for management position

(Manager: 1 = yes, 0 = no). We shall call this Model 1. The coefficient of partial

determination ( ) of each of the 6 predictors are, respectively,

0.2807, 0.0386, 0.0317, 0.0141, 0.0958, and 0.1201.

Model 2 is the regression analysis where the dependent variable is Unemploy and the

independent variables are Age and Manager. The results of the regression analysis are

given below:

Referring to Table 17-10, Model 1, there is sufficient evidence that the number of

weeks a worker is unemployed due to a layoff depends on at least one of the

explanatory variables at a 10% level of significance.

True or False: A research analyst was directed to arrange raw data collected on the yield

of wheat, ranging from 40 to 93 bushels per acre, in a frequency distribution. He should

choose 30 as the class interval width.

TABLE 8-8

The president of a university would like to estimate the proportion of the student

population that owns a personal computer. In a sample of 500 students, 417 own a

personal computer.

True or False: Referring to Table 8-8, a 99% confidence interval will contain 99% of the

student population who own a personal computer.

TABLE 8-12

A random sample of 100 stores from a large chain of 500 garden supply stores was

selected to determine the mean number of lawnmowers sold at an end-of-season

clearance sale. The sample results indicated a mean of 6 and a standard deviation of 2

lawnmowers sold. A 95% confidence interval (5.623 to 6.377) was established based on

these results.

True or False: Referring to Table 8-12, of all possible samples of 100 stores taken from

the population of 1,000 stores, 95% of the confidence intervals developed will contain

the true population mean within the interval.

TABLE 16-13

Given below is the monthly time-series data for U.S. retail sales of building materials

over a specific year.

The results of the linear trend, quadratic trend, exponential trend, first-order

autoregressive, second-order autoregressive and third-order autoregressive model are

presented below in which the coded month for the 1st month is 0:

Linear trend model:

Quadratic trend model:

Exponential trend model:

First-order autoregressive:

Second-order autoregressive:

Third-order autoregressive:

Below is the residual plot of the various models:

True or False: Referring to Table 16-13, the best model based on the residual plots is the

exponential-trend regression model.

True or False: TABLE 17-3

A financial analyst wanted to examine the relationship between salary (in $1,000) and 4

variables: age (X1 = Age), experience in the field (X2 = Exper), number of degrees (X3 =

Degrees), and number of previous jobs in the field (X4 = Prevjobs). He took a sample of

20 employees and obtained the following Microsoft Excel output:

SUMMARY OUTPUT

Regression Statistics

ANOVA

Referring to Table 17-3, the F test for the significance of the entire regression

performed at a level of significance of 0.01 leads to a rejection of the null hypothesis.

TABLE 14-10

You worked as an intern at We Always Win Car Insurance Company

last summer. You notice that individual car insurance premiums

depend very much on the age of the individual and the number of

tra&c tickets received by the individual. You performed a regression

analysis in EXCEL and obtained the following partial information:

True or False: Referring to Table 14-10, to test the signi,cance of the

multiple regression model, the null hypothesis should be rejected

while allowing for 1% probability of committing a type I error.

True or False: The question: “Have you used any form of illicit drugs over the past 2

months?” will most likely result in measurement error if the question is answered.

The personnel director at a large company studied the eating habits of the company’s

employees. The director noted whether employees brought their own lunches to work,

ate at the company cafeteria, or went out to lunch. The goal of the study was to improve

the food service at the company cafeteria. This type of data collection would best be

considered as

A) an observational study.

B) a designed experiment.

C) a random sample.

D) a quota sample.

TABLE 10-5

To test the effectiveness of a business school preparation course, 8 students took a

general business test before and after the course. The results are given below.

Referring to Table 10-5, the value of the standard error of the difference scores is

A) 65.027.

B) 60.828.

C) 22.991.

D) 14.696.

TABLE 17-10