SFtraveler wrote:DS Problem - What is most efficient way to solve this DS problem? Please provide step-by-step solution.
If the ratio of positive integers a, b, and c is 1:2:3, what is the value of a+b+c?
1) c-a = 8
2) b-a = 4
The most efficient approach is to recognize that we don't have to solve; we need only determine whether there is sufficient information to solve.
Statement 1:
c-a = 8.
Since a
c = 1:2:3, a/c = 1/3.
2 variables, 2 different linear equations. We can solve for a and c, then use the ratio of a
c to solve for b.
Sufficient.
Statement 2:
b-a =4.
Since a
c = 1:2:3, a/b = 1/2.
2 variables, 2 different linear equations. We can solve for a and b, then use the ratio of a
c to solve for c.
Sufficient.
The correct answer is
D.
We should do NO math for this problem. We should recognize that since each statement gives us a second linear equation, each is sufficient to solve for all 3 variables.
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c=1:2:3 => a/c=1/3, a/b=1/2, b/c=2/3 => solving the system of equations
