n is a positive integer. What is the remainder when n is divided by 6?
(1) n is a multiple of 3.
(2) When n is divided by 2, the remainder is 1.[/quote]
From (1) , n=3a i.e 3,6,9,12,15,18....etc.
This divided by 6 will give either 0 or 3 as remainder. Hence NOT SUFFICIENT
From (2) , n=2b+1. Consider putting values of b as 1,2,3....etc, n=3,5,7,9
Values of n are multiples and remainders too will be different for each one of them.
Combining (1) + (2) , n = 6K + 3, which when divided by 6 will give remainder as -
6K/6 + 3/6 => 0 + 3 => 3 (remiander). Correct Answer is C.
Pls note n =6K +3 can be found as follows -
3a = 2b+1
=> a = (2b+1)/3
Putting values of b as 1,2,3...etc.
b=1 ,a =1
b=2,a = 5/3 (not an integer)
b=3,a= 7/3 (not an integer)
b=4,a=3
We see least value of n can be found when a =1 or b =1. Incorporating this n=3
N = least number obtained + (LCM of divisors)*K , where K is a non negative integer.
= 3 + 3a*2b = 3+6ab =(3+6K)