set 6-13

[crazy800]

What is the remainder when the positive integer n is divided by 3?
(1) The remainder when n is divided by 2 is 1.
(2) The remainder when n + 1 is divided by 3 is 2.

[ankit0uc]

IMO B


1. try n=2q+1

Put q =1, 2 , 3, 4, 5

When we divide n by 3 we get different remained.

2. n=3q+2-1

Put q =1, 2,3, 4, 5

When we divide n by 3 we get just one remainder. ie 1

Hence Suff

B

[genius_in_the_gene]

We can represent the question as n=3x+r. What is r?

1) Given n=2x+1. But this doesn't give enough info about divisibility by 3.
e.g, x can be 1, so n=3 and r(reminder when divided by 3)=0
x=2, n=5, r=2
Insuff

2) n+1=3x+2
n=3x+1. This proves that r=1 so sufficient.

Hence the answer is B

[bose]

i got b too
stmt 1 insuff as n=3 and 7 give diff result
stmt 2 suff as n+1=3q+2 so n=3q+1 so rem is 1