Remainder

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Remainder

by moneyman » Mon Nov 24, 2008 5:53 am
Check it out
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Remainder DS ANS  C.JPG
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by orel » Mon Nov 24, 2008 7:03 am
we can rewrite the given info as following:

n=3x+2 and t=5y+3

to find the remainder when nt is divided by 15:

statement (1): n-2 is divisible by 5
3x+2-2=3x is divisible by 5, which means x is divisible by 5. so, 3x is divisible by 15, with the remainder "0".
when divided by 15, nt will have a remainder "0".

SUFFICIENT

Statement (2): t is divisible by 3

5y+3 is divisible by 3....5y is divisible by 3, which means 5y+3 is divisible by 15 with the remainder 3.
Since n is divided by 3 with the remainder 2, when multiplied by t, it doesn't give precise answer, so insufficient.

So, the OA is A

correct?

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by logitech » Mon Nov 24, 2008 8:01 am
n=3a+2
t=5b+3

St 1) n-2 = 5x ; we know that n-2 =3a so n-2=15t and n = 15t+2

no information on t - insuf

St 2) t=5b+3 ; t=3y ..5b+3 = 3y ...5b=3(y-1) and t = 15m + 3

no info on n - insuf

ST 1+2)
(15t+2) (15m+3) / 15

Remainder: 2x3 = 6

Hence, C
Last edited by logitech on Mon Nov 24, 2008 9:10 am, edited 1 time in total.
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by Tryingmybest » Mon Nov 24, 2008 8:43 am
Logitech- How did u get this? What is the significance of 6?
(15t+2) (15m+3) / 6

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by logitech » Mon Nov 24, 2008 9:11 am
Tryingmybest wrote:Logitech- How did u get this? What is the significance of 6?
(15t+2) (15m+3) / 6
Sorry It was a typo. I was thinking of the result ;-) I edited my post
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by Tryingmybest » Mon Nov 24, 2008 9:19 am
Big Brother is watching u :)

Just kidding.. Wonderful solution.

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by logitech » Mon Nov 24, 2008 9:22 am
Tryingmybest wrote:Big Brother is watching u :)
I appreciate that. And also I want to thank moneyman for all of these great official questions.

And I know his test is very soon. GOOD LUCK man!
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by Tryingmybest » Mon Nov 24, 2008 9:35 am
Logitech -Sorry to bug u again

St 2) t=5b+3 ; t=3y ..5b+3 = 3y ...5b=3(y-1) and t = 15m + 3

If 5b=3(y-1) => t = 3(y-1)+3 how did u get t = 15m + 3??

Please enlighten me.

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by logitech » Mon Nov 24, 2008 9:50 am
5b=3(y-1) well since 5b is also a multiple of 3

LCM(3:5) = 15

so for example

5x3 = 3 (6-1)

So this actually tells us 5b has 3 as a factor.

and t = 15m + 3

Did I confuse you even more ?
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by Tryingmybest » Mon Nov 24, 2008 10:05 am
Or in other words can I say

5b is a multiple of 3 => b must be a multiple of 3
=> 5b will be of the series 15,30,45 etc
=> 15 m (where m must be a multiple of 3)

It makes perfect sense now.. Thanks!!

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by moneyman » Tue Nov 25, 2008 12:40 am
Test is tomorrow..Thanks Logitech
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by logitech » Tue Nov 25, 2008 12:52 am
I will pray for you. You have been working hard. Go and claim what is yours.

Shall the force be with you!
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by moneyman » Tue Nov 25, 2008 12:56 am
Thanks bro..appreciate it
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