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GMAT Club > Tests > m14 (Q21) [#permalink]
27 Feb 2011, 21:38
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GMAT Club > Tests > m14 (Q21)
If a and b are positive integers, is 10^a + b divisible by 3?
1. b/2 is an odd integer. 2. the remainder of b/10 is b.
Statements (1) and (2) combined are insufficient. Consider b=2(the answer is "yes") and b=6 (the answer is "no").
The correct answer is E.
Can anyone help me out in solving this, I feel answer is C. Would be true only for b=2 in common.
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Re: GMAT Club > Tests > m14 (Q21) [#permalink]
27 Feb 2011, 22:09
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Statement 1 tells us that b is an even integer of the form odd*2, so b can be 2, 6, 10 etc.. Lets say a = 1, then 10^a+b is divisible by 3 when b is 2 but not when b is 6 so insufficient.
Statement 2 tells us that b is less than 10, but then b can be 1,2,3 etc. and divisibility of 10^a+b for these values of b would be different (yes as well as No) so insufficient.
Combining 1 and 2 will give that b can be 2 or 6 but the answer for divisibility is different for 2 and 6, so insufficient once again. Hence answer is E.
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Re: GMAT Club > Tests > m14 (Q21) [#permalink]
27 Feb 2011, 23:00
good one....got it...
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Re: GMAT Club > Tests > m14 (Q21)
[#permalink]
27 Feb 2011, 23:00
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