CMA Foundation · Fundamentals of Business Mathematics and Statistics · Ratios, Variations and Proportions
If 4, x and 25 are in continued proportion with x positive, and the mean proportional x is the second term, what is the value of (x + 4) : (25 − x)?
The ratio is 14:15. Since 4, x and 25 are in continued proportion, x squared is 100, so x is 10. Then x plus 4 is 14 and 25 minus x is 15, giving the ratio 14:15.
- A10:15
- B3:2Correct
- C7:10
- D14:15
Explanation
x² = 4 × 25 = 100, so x = 10. Then x + 4 = 14 and 25 − x = 15, so the ratio is 14:15. The option 3:2 is incorrect since it comes from 15:10, which reverses and misuses the terms.
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