/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Q114E Using z-scores for grades. At on... [FREE SOLUTION] | 91影视

91影视

Using z-scores for grades. At one university, the students are given z-scores at the end of each semester rather than the traditional GPAs. The mean and standard deviation of all students鈥 cumulative GPAs, on which the z-scores are based, are 2.7 and .5, respectively.

a. Translate each of the following z-scores to the corresponding GPA: z = 2.0, z = -1.0, z = .5, z = -2.5.

b. Students with z-scores below 鈭1.6 are put on probation. What is the corresponding probationary GPA?

c. The president of the university wishes to graduate the top 16% of the students with cum laude honors and the top 2.5% with summa cum laude honors. Where (approximately) should the limits be set in terms of z-scores? In terms of GPAs? What assumption, if any, did you make about the distribution of the GPAs at the university?

Short Answer

Expert verified
  1. In terms of GPA, the scores will be 3.7, 2.2, 2.95 and 1.45, respectively.
  2. 1.9
  3. Z-score for the top 16% and the top 2.5% are 1 and 2, respectively, and GPA scores are 3.2 and 3.7, respectively.

Step by step solution

01

Calculation of the GPA scores

The translations from z-scores to GPA are shown below:

x1 = Mean + zStandarddeviation= 2.7 + 20.5= 3.7x2 = Mean + zStandarddeviation= 2.7 - 10.5= 2.2x3 = Mean + zStandarddeviation= 2.7 + 0.50.5= 2.95x4 = Mean + zStandarddeviation= 2.7 - 2.50.5= 1.45

Here x1 represents the corresponding GPA for z score of 2.

Here x2 represents the corresponding GPA for z score of -1.

Here x3 represents the corresponding GPA for z score of 0.5.

Here x4 represents the corresponding GPA for z score of 1.45.

02

Calculation of the probationary GPA score

The calculation of probationary GPA (x5) is shown below:

x5 = Mean + zStandarddeviation= 2.7 - 1.60.5= 1.9

03

Determination of z-scores, GPA and assumption

For the top 16 percent, the z-score must be 1 for having 1 standard deviation above the mean and for the top 2.5 percent, the z-score must be 2 for having 2 standard deviations above the mean. The GPA (x6) for z-score of 1 and GPA (x7) for z-score of 2, respectively are calculated below:

x6 = Mean + zStandarddeviation= 2.7 + 10.5= 3.2x7 = Mean + zStandarddeviation= 2.7 + 20.5= 3.7

There have been no assumptions made for this for the purpose of calculation.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Made-to-order delivery times.Refer to the data on delivery times for a made-to-order product, Exercise 2.34 (p. 87). The delivery times (in days) for a sample of 25 orders are repeated in the accompanying table. (Times marked by an asterisk are associated with customers who subsequently placed additional orders with the company.) Identify any unusual observations (outliers) in the data set, and then use the results to comment on the claim that repeat customers tend to have shorter delivery times than one-time customers.

50* 64* 56* 43* 64* 82* 65* 49* 32* 63* 44* 71 54* 51* 102 49* 73* 50* 39* 86 33* 95 59* 51* 68

The Apprenticecontestants鈥 performance ratings.Refer to the Significance(April 2015) study of contestants鈥 performance on the popular TV show The Apprentice, Exercise 2.9 (p. 73). Recall that each of 159 contestants was rated (on a 20-point scale) based on their performance. The accompanying Minitab printout gives the mean and standard deviation of the contestant ratings, categorized by highest degree obtained (no degree, first degree, or postgraduate degree) and prize (job or partnership with Lord Sugar).

Descriptive Statistics: Ratings

Results for Prize = Job

Variable

Degree

N

Mean

StDev

Minimum

Maximum

Rating

First

54

7.796

4.231

1.000

17

None

35

7.457

4.388

1.000

20

Post

10

9.80

4.54

2.000

17

Results for Prize = Partnership

Variable

Degree

N

Mean

StDev

Minimum

Maximum

Rating

First

33

8.212

4.775

1.000

20.00

None

21

10.62

4.83

3.000

20.00

Post

6

6.50

3.33

2.000

12.00

a.Give a practical interpretation of the mean rating for contestants with a first (bachelor鈥檚) degree who competed for a job with Lord Sugar.

b.Find an interval that captures about 95% of the ratings for contestants with a first (bachelor鈥檚) degree who competed for a job with Lord Sugar.

c.An analysis of the data led the researchers to conclude that 鈥渨hen the reward for winning . . . was a job, more academically qualified contestants tended to perform less well; however, this pattern is reversed when the prize changed to a business partnership.鈥 Do you agree? Explain.

Nuclear power plants.According to the Nuclear Energy Institute (NEI), 62 nuclear power plants were operating in the United States in 2015. The table at top of the next column lists the 30 states that operate nuclear power

plants, the number of plants in each state, and whether the state has passed legislation supporting nuclear energy expansion (regulated) or not (deregulated).

a.Find the mean, median, and mode of the number of power plants per state. Interpret these values.

b.Repeat part afor the regulated states only.

c.Repeat part afor the deregulated states only.

d.Compare the results, parts band c.What inference can you make about the impact that state regulation has on the number of nuclear power plants?

e.Eliminate the state with the largest number of power plants from the data set and repeat part a.What effect does dropping this measurement have on the measures of central tendency found in part a?

f.Arrange the 30 values in the table from lowest to highest. Next, eliminate the lowest two values and the highest two values from the data set and find the mean of the remaining data values. The result is called a 10% trimmed meanbecause it is calculated after removing the highest 10% and the lowest 10% of the data values. What advantages does a trimmed mean have over the regular arithmetic mean?

State

Status

Number of Power Plants

Alabama

Regulated

2

Arizona

Regulated

1

Arkansas

Regulated

1

California

Regulated

1

Connecticut

Deregulated

1

Florida

Regulated

3

Georgia

Regulated

2

Illinois

Deregulated

6

Iowa

Deregulated

1

Kansas

Regulated

1

Louisiana

Regulated

2

Maryland

Deregulated

1

Massachusetts

Deregulated

1

Michigan

Deregulated

3

Minnesota

Regulated

2

Mississippi

Regulated

1

Missouri

Regulated

1

Nebraska

Regulated

2

New Hampshire

Deregulated

1

New Jersey

Deregulated

3

New York

Deregulated

4

North Carolina

Regulated

3

Ohio

Deregulated

2

Pennsylvania

Deregulated

5

South Carolina

Regulated

4

Tennessee

Regulated

2

Texas

Deregulated

2

Virginia

Regulated

2

Washington

Regulated

1

Wisconsin

Deregulated

1

Salary offers to MBAs.Consider the top salary offer (in thousands of dollars) received by each member of a sample of 50 MBA students who graduated from the Graduate School of Management at Rutgers, the state university of New Jersey. Descriptive statistics and a box plot for the data are shown on the XLSTAT printouts at the top of the next column. [Note:The 鈥+鈥 on the box plot represents the location of the mean.]

a.Find and interpret the z-score associated with the highest salary offer, the lowest salary offer, and the mean salary offer. Would you consider the highest offer to be unusually high? Why or why not?

b.Based on the box plot for this data set, which salary offers (if any) are suspect or highly suspect outliers?

STEM experiences for girls. The National Science Foundation (NSF) sponsored a study on girls鈥 participation in informal science, technology, engineering, or mathematics (STEM) programs. The results of the study were published in Cascading Influences: Long-Term Impacts of Informal STEM Experiences for Girls (March 2013). The researchers sampled 174 young women who recently participated in a STEM program. They used a pie chart to describe the geographic location (urban, suburban, or rural) of the STEM programs attended. Of the 174 STEM participants, 107 were in urban areas, 57 in suburban areas, and 10 in rural areas.

a. Determine the proportion of STEM participants from urban areas.

b. Determine the proportion of STEM participants from suburban areas.

c. Determine the proportion of STEM participants from rural areas.

d. Multiply each proportion in parts a鈥攃 by 360 to determine the pie slice size (in degrees) for each location.

e. Use the results, part d, to construct a pie chart for the geographic location of STEM participants.

f. Interpret the pie slice for urban areas.

g. Convert the pie chart into a bar graph. Which, in your opinion, is more informative?

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.