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If two integers x,y (x>y) are selected from -5 to 4(inclu

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If two integers x,y (x>y) are selected from -5 to 4(inclu

by Max@Math Revolution » Mon Jul 25, 2016 4:56 am
If two integers x,y (x>y) are selected from -5 to 4(inclusive), how many cases are there?
A. 15
B. 18
C. 36
D. 45
E. 90

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by Brent@GMATPrepNow » Mon Jul 25, 2016 6:07 am
Max@Math Revolution wrote:If two integers x,y (x>y) are selected from -5 to 4(inclusive), how many cases are there?
A. 15
B. 18
C. 36
D. 45
E. 90
There are 10 integers from -5 to 4 inclusive.
Choose ANY 2 integers and make x = the larger integer and make y = the smaller integer.
Since the order in which we select the two numbers does not matter, we can use COMBINATIONS.
We can select 2 integers from 10 integers in 10C2 ways
10C2 = 45

Answer: D

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by Max@Math Revolution » Tue Jul 26, 2016 5:23 pm
10C2=45
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