CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
If x varies directly as y, and x = 12 when y = 8, what is the value of x when y = 20?
The value of x is 30. Since x varies directly as y, x/y is constant at 12/8 = 1.5, so when y is 20, x equals 1.5 multiplied by 20, which gives 30.
- A30Correct
- B24
- C32
- D19.2
Explanation
Direct variation gives x = ky. From 12 = k × 8, k = 1.5. Then x = 1.5 × 20 = 30. The value 24 results from adding the difference 12 to 12 instead of using the constant of proportionality.
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