When positive integer n is divided by 3, the remainder is 2; and when positive integer t is divided by 5, the remainder is 3. What is the remainder when the product nt is divided by 15 ?
(1) n- 2 is divisible by 5.
(2) t is divisible by 3.
GMAT Prep DS Question
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From 1:
Different possible values of n are 17, 32, 47 ....
But this doesn't tell us anything about t.
t still can have diffferent values like 8, 13, 18 ....
Different combination of these numbers to calculate nt, would result in different remainders when nt is divided by 15
so [1] is not sufficient
From 2 :
t can have values like 18
Now any combination of nt divided by 15 would produce a remainder of 2
So [1] and [2] together are sufficient.
Whats the OA by the way?
Thanks
Different possible values of n are 17, 32, 47 ....
But this doesn't tell us anything about t.
t still can have diffferent values like 8, 13, 18 ....
Different combination of these numbers to calculate nt, would result in different remainders when nt is divided by 15
so [1] is not sufficient
From 2 :
t can have values like 18
Now any combination of nt divided by 15 would produce a remainder of 2
So [1] and [2] together are sufficient.
Whats the OA by the way?
Thanks
first,
n = 2, 5, 8, 11, 14, 17, ....
t = 3, 8, 13, 18,
(1)
narrows n down to => 2, 17, 32, etc.
INSUFF
(2)
narrows t down to => 3, 18, etc
INSUFF
together any value of n and t from (1) and (2) => remainder when divided by 15 is 6.
SUFF => Ans (C).
n = 2, 5, 8, 11, 14, 17, ....
t = 3, 8, 13, 18,
(1)
narrows n down to => 2, 17, 32, etc.
INSUFF
(2)
narrows t down to => 3, 18, etc
INSUFF
together any value of n and t from (1) and (2) => remainder when divided by 15 is 6.
SUFF => Ans (C).