Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
All you math geniuses
#1
Below is a probability problem, that I can't come up with the same answer as ETS on the sample college math exam. Can anyone help?

[I]The faces of a fair cube are numbered 1 through 6; the probability of rolling any number from 1 through 6 is equally likely. If the cube is rolled twice, what is the probability that an even number will appear on the top face in the first roll or that the number 1 will appear on the top face in the second roll[/I]

So as explained in the "Cracking the Clep" book, I figured the first roll would be 3/6 and the second roll would be 1/6. Add those together and you get 4/6, reduced to 2/3. That is one of the answers but they say the correct answer is 7/12. Where am I going wrong?

Urg, I am never gonna get through this exam.
__________________
__________________

cate
BS (UMUC) in 2010, 30+ years in the making!!

Intro to Computing 63
Astronomy 63
Technical Writing 62
Principles of Mgt 71
Principles of Marketing 68
Substance Abuse 467
College Math 56
Principles of Finance 425
Principles of Statistics 458

Exams: ALL DONE!!!!!!!!!!

GRADUATION--UMUC--MAY 15, 2010 (unbelievable)
[-] The following 1 user Likes categ's post:
  • will1030
Reply
#2
This is from Yahoo answers. Looks like the same problem.
Good Luck,
Bob


Fair cube probability question? - Yahoo! Answers
A.A. Penn State
B.A. Charter Oak State College
M.B.A. Andrew Jackson University In Progress
[-] The following 1 user Likes Bob's post:
  • will1030
Reply
#3
You are my hero! How did you find that, it was exactly the same problem?

Thank you!
__________________
__________________

cate
BS (UMUC) in 2010, 30+ years in the making!!

Intro to Computing 63
Astronomy 63
Technical Writing 62
Principles of Mgt 71
Principles of Marketing 68
Substance Abuse 467
College Math 56
Principles of Finance 425
Principles of Statistics 458

Exams: ALL DONE!!!!!!!!!!

GRADUATION--UMUC--MAY 15, 2010 (unbelievable)
Reply
#4
Quote:You are my hero! How did you find that, it was exactly the same problem?

I cut and pasted the first half of the problem only into google and that brought up a different problem, so I pasted the second half only and up came your problem. Glad I could help.
Bob
A.A. Penn State
B.A. Charter Oak State College
M.B.A. Andrew Jackson University In Progress
Reply
#5
Once again. InstantCert Forum is my hero. Thank you!!!
AP - 24 Credits - Microeconomics (3), Macroeconomics (3), World History (3), English Language and Composition (5), American Government (3), Human Geography (5)

CLEP - 27 Credits - College Mathematics (68), Natural Sciences (57), History of the U.S. 1 (61), Analyzing and Interpreting Literature (67), Financial Accounting (55), Principles of Management (67), Principles of Marketing (64), Introductory Business Law (57), Introduction to Educational Psychology (65)

DSST - 15 Credits - Business Ethics and Society (423), Management Information Systems (422), Principles of Public Speaking (466), Principles of Finance (435), Human Resources Management (457)

Sophia Learning - 3 Credits - Introductory Psychology

COSC Classes - 31 Credits

Projected B.S. in Business Administration Completion Date: August 2022 (Before I'm 18 Smile

God Bless the USA!
Reply
#6
The question is asking what the odds are that one or  the other would happen. 2/3 is on the right track, but you forgot a step.

In fact, 2/3 would be the correct answer if the question was changed from:

Quote:The faces of a fair cube are numbered 1 through 6; the probability of rolling any number from 1 through 6 is equally likely. If the cube is rolled twice, what is the probability that an even number will appear on the top face in the first roll or that the number 1 will appear on the top face in the second roll?

to

Quote:The faces of a fair cube are numbered 1 through 6; the probability of rolling any number from 1 through 6 is equally likely. If the cube is rolled twice, what is the probability that an even number will appear on the top face in the first roll, that the number 1 will appear on the top face in the second roll, or that both would occur simultaneously?

The word "or" means that we actually need to exclude the option of both happening.


If the probability of rolling an even face on the first roll is R1 and the probability of rolling a 1 on the second roll is R2, then we can calculate the likelihood for each.

R1 = Number of even faces / number of total faces = 3/6
R2 = Number of faces with a value of 1 / number of total faces = 1/6

The probability of the independent occurrence of either OR both events, removing constraints, is simply Rn = R1+R2+R3...
Or: 2/3

The intersection of probabilities can be calculated using Rn = R1*R2*R3...
Thus: R1*R2 = R3, R1 * R2 = 3/36 = 1/12
R3 = 1/12

To find the union of probabilities, you take the probability of independent occurrence minus the intersection of probabilities, or 2/3 - 1/12 = 8/12 - 1/12 = 7/12
Master of Business Administration, Universidad Isabel I, 2021
Master in Management & Team Management, Universidad Isabel I, 2021
Master in International Trade, Universidad Isabel I, 2021
Master in Supply Chain Management, Universidad Isabel I, 2021
Master in Project Management, Universidad Isabel I, 2023

BS Information Technology, Western Governors University, 2017
AAS Cybersecurity, Community College, 2017
FEMA Emergency Management Certificate, 2017
Fundraising Specialization Certificate, Berkeley/Haas, 2020

Undergraduate Credits: 165 Semester Credits
Graduate Credits: 105 ECTS (52.5 Semester Credits)
Reply


Possibly Related Threads...
Thread Author Replies Views Last Post
Question The hardest kind of math is... LevelUP 5 852 04-29-2023, 12:44 AM
Last Post: bjcheung77
  Math Help Giantzebra 22 4,984 07-09-2019, 02:43 PM
Last Post: Giantzebra
  Simple Math Problem - It's been a while... NJGx03x871 5 2,520 06-29-2014, 05:25 PM
Last Post: Lindagerr

Forum Jump:


Users browsing this thread: 1 Guest(s)