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Intern
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When positive integer N is divided by 3, the remainder is 2. [#permalink]
24 Oct 2009, 09:08
Question Stats:
100% (00:00) correct
0% (00:00) wrong based on 0 sessions
1. When positive integer N is divided by 3, the remainder is 2. When integer T is divided by 5, the remainder is 3. What is the remainder when the product, NT, is divided by 15?
A) N-2 is divisible by 5. B) T is divisible by 3. • The correct answer is C.
2. Maria bought some pencils. Each pencil either cost 23 cents or 21 cents. How many 23c pencils did she buy?
A) Maria bought 6 Pencils B) The total value of the pencils = 130 cents. • The correct answer is B.
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Director
Joined: 01 Apr 2008
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Re: Could you help me out with this question? [#permalink]
24 Oct 2009, 10:13
Given: N = 3a+2, T = 5b+3 NT = 15ab + 9a + 10b + 6, for NT to be divisible by 15 we need to check the divisibility of each term by 15.
stmt1: N-2= 5c => N=5c+2 hence, 5c+2=3a+2 => 5c=3a, which means 'a' can take values such as 5,10,15...Thus the second term (9*multiple of 5) will be divisible by 15. We have no idea about 10b. Not suff.
stmt2: T = 3d 3d=5b+3 => 'b' can take values such as 3,6,...Thus the third term (10*multiple of 3) will be divisible by 15. We have no idea about 9a.
combining, the remainder will be 6/15 = 6. C
2) stmt1. We do not know anything about the total value, insuff. stmt2. Only possibility is 23*2 + 21*4 = 130. suff B.
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Re: Could you help me out with this question?
[#permalink]
24 Oct 2009, 10:13
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