IMO C
from 2: by knowing a numerator we can never say whether it will be terminating or nor
from 1: r/(225^2) = r/(15^4)
when r = 15^4 then it will be terminating
when r = (15^3)*5 then it will be non terminating.
Now combine 1 and 2 as 81 = 3^4
r/s = (3/15)^4 = (0.2)^4 is terminating.
Simple DS?
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Source: Beat The GMAT — Data Sufficiency |
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Brian@VeritasPrep
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Hey kmittal82:
Great question - and I'd also add this bit of GMAT strategy to it, too: use statement 2 to help you double-check statement 1.
Because the distinction between A and C comes down to "do you need statement 2 or not", statement 2 may well provide essential information. Therefore, if 1 seems sufficient on its own and 2 definitely doesn't, ask yourself why 2 is there.
Here, I thought a lot like you at first glance - 225 is a multiple of 9, so it looked like you were going to get something repeating like .1111111 out of it. But immediately when I saw statement 2 I though "that's a multiple of 9...twice", and that's what clicked my thinking back to the thought that:
1/9 = .1111111
2/9 = .2222222
etc.
8/9 = .8888888
but 9/9 = 1, because the 9s cancel each other out and you're left without a repeating decimal.
So then I recognized that as long as I can account for every 9 in the denominator with one in the numerator, the decimal will be determined by the other factors in the fraction.
Essentially, a closer look at 2 saved me from a way-too-quick assumptive answer on 1, and that happens enough that it's worth being aware of. My rule of thumb - if 1 seems sufficient and 2 seems pretty far from it, there's a great chance that 2 is there to clarify something that 1 doesn't on its own, so I should go back and reconsider 1, and reconsider it by thinking about what 1 has taught me.
Great question - and I'd also add this bit of GMAT strategy to it, too: use statement 2 to help you double-check statement 1.
Because the distinction between A and C comes down to "do you need statement 2 or not", statement 2 may well provide essential information. Therefore, if 1 seems sufficient on its own and 2 definitely doesn't, ask yourself why 2 is there.
Here, I thought a lot like you at first glance - 225 is a multiple of 9, so it looked like you were going to get something repeating like .1111111 out of it. But immediately when I saw statement 2 I though "that's a multiple of 9...twice", and that's what clicked my thinking back to the thought that:
1/9 = .1111111
2/9 = .2222222
etc.
8/9 = .8888888
but 9/9 = 1, because the 9s cancel each other out and you're left without a repeating decimal.
So then I recognized that as long as I can account for every 9 in the denominator with one in the numerator, the decimal will be determined by the other factors in the fraction.
Essentially, a closer look at 2 saved me from a way-too-quick assumptive answer on 1, and that happens enough that it's worth being aware of. My rule of thumb - if 1 seems sufficient and 2 seems pretty far from it, there's a great chance that 2 is there to clarify something that 1 doesn't on its own, so I should go back and reconsider 1, and reconsider it by thinking about what 1 has taught me.
Brian Galvin
GMAT Instructor
Chief Academic Officer
Veritas Prep
Looking for GMAT practice questions? Try out the Veritas Prep Question Bank. Learn More.
GMAT Instructor
Chief Academic Officer
Veritas Prep
Looking for GMAT practice questions? Try out the Veritas Prep Question Bank. Learn More.
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anantbhatia
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