Problem Solving

If k is a positive even integer, and 15k = x, which of the following must be true?

I. x is a multiple of 3.
II. x is a multiple of 5.
III. x = 30
(a) None

(b) I only

(c) II only

(d) I and II only

(e) I, II, and III


I answered e

adam15 wrote:If k is a positive even integer, and 15k = x, which of the following must be true?

I. x is a multiple of 3.
II. x is a multiple of 5.
III. x = 30
(a) None

(b) I only

(c) II only

(d) I and II only

(e) I, II, and III


I answered e

Good question..

we know that x= 15k

then x is a multiple of 15 which is a multiple of 5 and 3 .. I and II Must be true

Now let's use the information given in the prompt. K is even and x/k = 15 .. let's try some numbers

x = 30 k= 2
30/2 = 15

x=60 k= 4
60/4 = 15

We need must be true not maybe true.

IMO the answer is D

answer will be D. X can be any value as it is a multiple of 15.


Regards,
Viju

you are saying that k= x/15 must be even, for x=15, which is a multiple of 3, but k is not even.
thank you very tricky question

adam15 wrote:you are saying that k= x/15 must be even, for x=15, which is a multiple of 3, but k is not even.
thank you very tricky question

why K is not even ??? it's noted in the question and I used k=2 and 4 ... so what do you mean by k is not even ?