GRE Math : How to find the greatest or least number of combinations

Study concepts, example questions & explanations for GRE Math

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Example Questions

Example Question #43 : Permutation / Combination

Bryant is purchasing basketballs from the basketball store. If he is purchasing three basketballs and there are seven basketballs to choose from, how many different combinations of basketballs can he buy?

Possible Answers:

Correct answer:

Explanation:

Since in this problem the order of selection does not matter, we're dealing with combinations.

With  selections made from  potential options, the total number of possible combinations is

Since Bryant is buying three basketballs from a selection of seven, the number of possible combinations is

Example Question #41 : Permutation / Combination

At a restaurant there is a choice of ten entrees and six potential sides. If an entree comes with two unique sides, how many different dinner options are possible?

Possible Answers:

Correct answer:

Explanation:

Since in this problem the order of selection does not matter, we're dealing with combinations.

With  selections made from  potential options, the total number of possible combinations is

One option is chosen from the ten entrees, so the number of entree combinations is

Two options are chosen from the six sides, so the number of side combinations is

The total number of combinations is the product of these individual results:

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