What is the value of x + y?
1) mx + ny + xn + ym = 10
2) m + n = 6
1) mx + ny + xn + ym = 10
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 |
Statement 1 is sufficient. |
 |
Statement 1 is insufficient. |
|
Calculation is necessary. |
2) m + n = 6
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|
Statement 2 is sufficient. |
|
Statement 2 is insufficient. |
|
Calculation is necessary. |
1) mx + ny + xn
+ ym = 10
2) m + n = 6
| |
|
The statements together are
sufficient. |
|
The statements together are
insufficient. |
|
Calculation is necessary. |
1) mx + ny + xn + ym = 10
or, rearranging: ?
mx + my + nx + ny = 10
2) m + n = 6
| |
|
The statements together are
sufficient. |
|
The statements together are
insufficient. |
|
Calculation is necessary. |
Countinue
At this point, we can foresee combined sufficiency. Why? Because now,
having rearranged the equation in the form mx + my + nx
+ ny = 10, and knowing that m + n = 6, we can see
that this question is really testing our understanding of the distributive
property of multiplication (just a fancy way of saying a(b
+ c) = ab + ac). Notice that the question doesn’t
test this concept directly, since it would be too easy for this level.
So instead the testmakers try to sneak it past you in the guise of a Data
Sufficiency question.
We could continue
our manipulations and calculate.
All that work, though, would be unnecessary once we recognized that we
could reorganize the variables and replace m and n
with their sum.
Next to display next topic in the chapter.
Test Prep Lessons With Video Lessons and Explained MCQ