LUANDATO wrote:Is the integer x divisible by 3?
(1) The last digit in x is 3.
(2) (x + 5) is divisible by 6.
The OA is B.
Can any expert explain this DS question please? I don't understand it. Thanks.
(1) The last digit in x is 3.
If for example, x = 33, it is divisible by 3; however, x = 23, it is not divisible by 3. Insufficient.
(2) (x + 5) is divisible by 6.
Since (x + 5) is divisible by 6, it must be divisible by the factors of 6, i.e., 2 and 3.
Thus, (x + 5) is divisible by 3.
The rule of divisibility of 3 is that if the sum of the digits of a number is divisible by 3, the number is divisible by 3.
Since (x + 5) is divisible by 3, the sum of digits of x and 5 is divisible by 3, Since 5 is not divisible by 3, the number x divided by 3 must leave a remainder 1 so that 1 and 5 make 6, divisible by 3. Thus, x is not divisible by 3. Sufficient.
The correct answer:
B
Hope this helps!
-Jay
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