VJesus12 wrote:Is xy < 10?
(1) x < 5 and y < 2
(2) x < −3 and y < −1
The OA is the option E.
Could anyone explain this DS question to me? Please. I'd like to know how can I solve it. <i class="em em-confused"></i>
We have to determine whether xy < 10.
Let's understand this inequality better.
1. If xy < 0, i.e. xy is negative, the answer is Yes.
For xy < 0, one of x and y must be positive and the other must be negative.
2. If xy = 0, the answer is Yes.
For xy = 0, At least one of x and y must be 0.
3. If 0 < xy < 10, i.e. xy is positive but less than 10, the answer is Yes.
Let's see each statement one by one.
(1) x < 5 and y < 2
Case 1: Say x = y = -10
=> xy = -10*-10 = 100 > 10, the answer is No.
Case 2: Say x = -4 and y = -2
=> xy = -4*-2 = 8 < 10, the answer is Yes.
No unique answer. Insufficient.
(2) x < −3 and y < −1
Both the cases discussed above are applicable here too. Insufficient
(1) and (2) together
Both the cases discussed above are applicable here too. Insufficient
The correct answer:
E
Hope this helps!
-Jay
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