The ratio of two quantities is 3 to 4. If each of these quantities is decreased by 5, what is the ratio of these two new quantities?
A. 3/4
B. 8/9
C. 18/19
D. 23/24
E. It cannot be determined from the information given
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Let the two quantities be N and M. We know (a) N/M = 3/4. Is this enough to know (b) (N-5)/(M-5)? Certainly not. Take any two sets {N,M} filling that proportion (a) and you'll get different results in (b).
case 1
N=3, M=4 (obvious example) will solve (b) to (3-5)/(4-5) = 2
case 2
N=3x2, M=4x2 (the 3/4 proportion is obviously maintained) will solve (b) to (6-5)/(8-5) = 1/3
Results are obviously different, meaning that we cannot the new ratio of the two quantities - it will surely vary.
Correct answer would be (E)
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