CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
If x varies directly as y and inversely as z, and x = 6 when y = 4 and z = 2, then the value of x when y = 9 and z = 6 is:
The value of x is 4.5. Since x = ky/z, the first set of values gives k = 3. Substituting y = 9 and z = 6 gives x = 3 × 9 / 6 = 4.5.
- A4.5Correct
- B9
- C3
- D6
Explanation
x = k y / z. From 6 = k × 4/2, k = 3. Then x = 3 × 9/6 = 4.5. Check by ratio: (9/6)/(4/2) = 0.75, and 6 × 0.75 = 4.5. The option 9 results from multiplying by z instead of dividing.
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