MATHS integers

This topic has expert replies
Source: — Problem Solving |

Master | Next Rank: 500 Posts
Posts: 136
Joined: Sun Sep 28, 2008 8:20 pm
Location: fssf
Thanked: 17 times

by krazy800 » Fri Jun 04, 2010 2:05 pm
francoisph wrote:How many integers from 0 to 50, inclusive, have a remainder of 1 when divided by 3?
A.14 B.15. C.16 D.17 E.18
I am getting D (17)

50/3 = 16; there are 16 numbers between 3 to 50 that are divisible by 3

therefore there must be 16 numbers that are not divisible by 3 and leave a remainder 1

ex: 4, 7, 10 , ....49


apart from the above values, "1" if divided by 3 leaves a remainder 1

therefore, we have a total of 16 +1=17 numbers between 0 to 50 inclusive that leave a remainder 1 when divided by 3.

HTH!
Aiming High

Master | Next Rank: 500 Posts
Posts: 151
Joined: Thu Apr 22, 2010 4:07 pm
Thanked: 14 times

by Haaress » Fri Jun 04, 2010 2:53 pm
Krazy, I agree with you and I like ur method.

Alternative method:

0 < 3x + 1 < 50 , where x is an interger.

So, 3(0) + 1 = 1, 3(1) + 1 = 4, 3(2) + 1= 7, 3(3) + 1=10, ........ 3(16) + 1=49.

Thus, 16 - 0 + 1 = 17, meaning we have 16 ( from 1 - 16 and 1 when x is zero.

D

User avatar
Legendary Member
Posts: 1309
Joined: Wed Mar 17, 2010 11:41 pm
Thanked: 33 times
Followed by:5 members

by pradeepkaushal9518 » Fri Jun 04, 2010 9:55 pm
imo C is answer

we cant take 1 as it is not divisble by 3 1/3=0.33 can we say that remainder is 1...

hence 16 should be the answer

what is oa

Senior | Next Rank: 100 Posts
Posts: 57
Joined: Sun Jul 06, 2008 10:52 am
Thanked: 1 times
GMAT Score:640

by iikarthik » Sat Jun 05, 2010 12:02 am
Hi,

1 should be considered and the answer IMO is 17.

Pls post the OA.

Newbie | Next Rank: 10 Posts
Posts: 7
Joined: Mon Feb 15, 2010 6:08 pm
Thanked: 1 times

by gmatguytoday » Tue Jun 15, 2010 7:28 am
Can we get an OA on this please?

I have option C - 16 as the answer.

User avatar
Legendary Member
Posts: 1893
Joined: Sun May 30, 2010 11:48 pm
Thanked: 215 times
Followed by:7 members

by kvcpk » Tue Jun 15, 2010 8:36 am
Answer should be 17. D

User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Tue Jun 15, 2010 10:22 am
pradeepkaushal9518 wrote:imo C is answer

we cant take 1 as it is not divisble by 3 1/3=0.33 can we say that remainder is 1...

hence 16 should be the answer

what is oa
Hi,

every non-negative integer when divided by a positive integer provides a quotient and a remainder.

1 divided by 3 has a quotient of 0 and a remainder of 1.

Another way you can think of remainders is as the numerator in the fraction of a (non-simplified) mixed fraction.

For example, 7/3 can be written as 2 and 1/3. So, the remainder when we divide 7 by 3 is 1.

1/3 can be written as 0 and 1/3. So, the remainder when we divide 1 by 3 is also 1.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course

User avatar
Master | Next Rank: 500 Posts
Posts: 294
Joined: Wed May 05, 2010 4:01 am
Location: india
Thanked: 57 times

by amising6 » Tue Jun 15, 2010 9:49 pm
How many integers from 0 to 50, inclusive, have a remainder of 1 when divided by 3?
A.14 B.15. C.16 D.17 E.18

so basically we are looking for the number of the form 3k+1
where k can take the value of integer .
constraint being it should be between 0 to 50
3k+1
if k=0
then first such integer will be 1
next put k=1
we get intger as 4
so we can say last intger will be for k =16 i.e 3*16+1=49
total number of integer between 0 to 50 will be 1to 16
so 17 possible value