Ratios, Problem Solving: GMAT question of the day

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Ratios, Problem Solving: GMAT question of the day

GMAT question of the day, problem solving
Explanation:
Let m denote the strength of a 5 layer carbon tire and n denote the strength of an 8 layer carbon tire.

If we add one more layer to the 5 layer carbon tire, the strength becomes 120% of m or 1.2*m. Similarly, by adding 3 more layers, the strength of the 8 layer carbon will be given by

n = m * 1.2 * 1.2 * 1.2 = 1.728

The ratio of strengths = n/m = 1.728/1 = 1.73

The correct answer is B.