Carcass wrote:
When 24 is divided by the positive integer n, the remainder is 4. Which of the following statements about n must be true?
I. n is even
II. n is a multiple of 5
III. n is a factor of 20
A) III only
B) I and II only
C) I and III only
D) II and III only
E) I, II, and III
We have the following expression when an integer A is divided by an integer B.
A=B⋅Q+R where 0≤R<|B|.
A,B,Q and R are called a dividend, a divisor, a quotient and a remainder, respectively.
Don't forget the restriction about the remainder 0≤R<|B|.Since 24 is divided by a positive integer
n and its remainder is
4, we have
24=n⋅q+4 for some integer
q where
0≤4<n.
Thus we have
n⋅q=20 where
n>4.
It means
n is a factor of
20, greater than
4. The possible values of
n are
5,10 and
20.
Thus, II and III only are true.
Therefore, D is the right answer.