Is a*b*c divisible by 32?

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Is a*b*c divisible by 32?

by M7MBA » Thu May 31, 2018 1:23 am

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Is a*b*c divisible by 32?

(1) a, b and c are consecutive even integers.

(2) a*c < 0

The OA is the option C .

How can I show that the correct option is C? Could anyone give me some help? Please.
Source: — Data Sufficiency |

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by Vincen » Thu May 31, 2018 2:33 am

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Hi M7MBA.

Let's take a look at your question.
Is a*b*c divisible by 32?
First statement
(1) a, b and c are consecutive even integers.
We can have different cases:

- a=2, b=4 and c=6.
Then a*b*c=48 which is not divisible by 32. NO

- a=4, b=6 and c=8.
Then a*b*c=192 which is divisible by 32. YES

Since we got two different answers, then this statement is not sufficient.

Second statement
(2) a*c < 0
This statement just tells us that "a" and "c" have different signs. We can have the following cases:

- a=-2, b=1, c=4
Then a*b*c=-8 which is not divisible by 32. NO

- a=4, b=-1, c=-8
Then a*b*c=32 which is divisible by 32. YES

Again, since we got two different answers, then this statement is not sufficient.

Both statements together
(1) a, b and c are consecutive even integers.
(2) a*c < 0
Now, we know that "a, b" and "c" are consecutive even integers and we also know that "a" and "c" have different signs. The unique case that holds these two condition s when b=0:

a=-2, b=0, c=2 or c=-2, b=0, a=2

In any case, we obtain a*b*c=0, and 0 is divisible by any number different from zero.

Therefore, in this case, a*b*c is divisible by 32 and it is the unique answer. YES

In conclusion, using both statements is sufficient.

The OA is the option C.

Regards.