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GMAT Combinatorics 1.1: Practice Problems

Posted by Mark Skoskiewicz on Tue, Dec 27, 2011 @ 03:45 AM

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This post will give you some GMAT practice problems related to the post GMAT Combinatorics 1.0: Introduction. These will not be GMAT type problems as MyGuru takes a bottom-up approach to test prep. We want out students to learn the fundamentals first. At a later point we'll focus on useful tricks and traps to avoid in the problems solving and data sufficiency format.

1. Suppose you perform the following experiment - You flip a coin 5 times and record the results. How many different outcomes are there?

2.0 You receive a new debit card in the mail and you are asked to create a new PIN (Personal Identification Number) for your debit card. The PIN must be 4 digits long and each digit must be one of the numbers 0 - 9. You can use the same digit more than once. How many possible PIN numbers are there?

2.1 Same as 2, but now you can use each digit only once.

2.2 Same as 2, but now you can use each digit only once and you cannot begin the PIN with a zero.

3. Sam, Sally, Xanthar, and their parents drive to the park in their Prion (a Prius that has been modified by Xanthar for hydrogen ion technology). If the two parents sit in the front and Sam, Sally, and Xanthar sit in the back seat, how many ways can the family be arranged in the car.

4.0 You roll two die. How many possible outcomes are there?

4.1 Same as 4.0. How many ways can you get tow even numbers?

4.2 Same as 4.0. How many ways can you get two odd numbers?

4.3 Same as 4.0. How many ways can you get one even and one odd number?

4.4 Same as 4.0. Now take the sum of the two upward facing numbers. How many ways can the sum be an even number?

4.5 Same as 4.0. Now take the product of the two upward facing numbers. How many ways can the product be an even number?

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