CMA Foundation · Fundamentals of Business Mathematics and Statistics · Ratios, Variations and Proportions
A varies directly as B and inversely as the square of C. When B = 8 and C = 2, A = 6. Find A when B = 12 and C = 3.
A equals 4. The relation is A = kB/C²; the given values yield k = 3, and substituting B = 12 and C = 3 gives 3 × 12 divided by 9, which equals 4.
- A4Correct
- B3
- C6
- D2.25
Explanation
A = kB/C². From 6 = k×8/4, k = 3. Then A = 3×12/9 = 4. The option 3 comes from using C instead of C² in a mistaken way, and 6 ignores the changes altogether.
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