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Re: If x, y and z are nonzero numbers is xz = 12 ?
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05 Dec 2015, 13:06
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
If x, y and z are nonzero numbers is xz = 12 ?
(1) x^2*y*z =12xy
(2) z/4 =3/x
There are 2 variables (x,z) and 2 equations are given by the 2 conditions, so there is high chance (C) will become the answer.
Looking at the conditions together,
condition 1) xz=12 (xz does not equal 0, so we can divide both sides by xz)
Condition 2) xz=12 so this answers the question 'yes' and the condition is hence sufficient
The answer becomes (D).
For cases where we need 2 more equations, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E.