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Source: — Data Sufficiency |

by beny » Thu Aug 23, 2007 10:37 am
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by radhika1306 » Thu Aug 23, 2007 11:17 am
can u explain
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by beny » Thu Aug 23, 2007 12:25 pm
Imagine x=8/9=64/72 and y=1/8=9/72.

In this case, x+y=73/72.

However, we know that x is strictly less than 8/9 and y is strictly less than 1/8. That's fine. Set it so that x+y=72.5/72. Because in the case of equality, the sum equals 73/72, you know that there is a case which satisfies both "less than" criteria which sums to 72.5/72 (it's not worth it to solve out the fraction, you just need to realize that one exists... i.e., if x=7.999999/9 and y=.99999999/8 ). This sum is greater than one.

On the other hand, if x=y=0, the sum is definitely less than 1.
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by radhika1306 » Fri Aug 24, 2007 5:10 am
Thanks:)
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