Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 350,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

If each of the digits can be used, as many times as [#permalink]
25 Feb 2008, 11:55

If each of the digits can be used, as many times as necessary, what is the probability of creating a four-digit number that is divisible by four and that begins and ends with a prime number? (A) 1/18 (B)1/25 (C)2/25 (D) 1/9 (E) 4/25 _________________

You tried your best and you failed miserably. The lesson is 'never try'. -Homer Simpson

If each of the digits can be used, as many times as necessary, what is the probability of creating a four-digit number that is divisible by four and that begins and ends with a prime number? (A) 1/18 (B)1/25 (C)2/25 (D) 1/9 (E) 4/25

If each of the digits can be used, as many times as necessary, what is the probability of creating a four-digit number that is divisible by four and that begins and ends with a prime number? (A) 1/18 (B)1/25 (C)2/25 (D) 1/9 (E) 4/25

= (4 x 10 x 5 x 1)/3000 = 1/15

hmmm. whats the source?

1000's place = 2, 3, 5 and 7. so 4 times 100's place = all 10 digits so 10 times 10's place = only 1, 3, 5, 7 and 9. so 5 times unit place = only 2 so 1 time

so multiply them = 4x10x5x1 = 200. total = 9x10x10x10 = 9000 (not 3000)

1000's place = 2, 3, 5 and 7. so 4 times 100's place = all 10 digits so 10 times 10's place = only 1, 3, 5, 7 and 9. so 5 times unit place = only 2 so 1 time

so multiply them = 4x10x5x1 = 200. total = 9x10x10x10 = 9000 (not 3000)

the last digit has to be equal to 2, the third digit has to be an odd number (22 is not divisible by 4, 12 is).

The second digit doesn't matter, the first digit is either 2,3,5 or 7. The second and third digits don't impact divisibility by 4 because 100 is divisible by 4.

i dont understand why the units digit must be the digit 2.

the number is divisible by 4 -> the last digit has to be even the last digit is a prime number -> the last digit is equal to 2 -> the only even prime number

My three goals of business school: entrepreneurship, network, and professor mentor. I want to build something. I want to meet new people and create life-long friendships. I want to...

One thing I did not know when recruiting for the MBA summer internship was the following: just how important prior experience in the function that you're recruiting for...