ABC26GN2914 · Ratio and Proportion

Subject: General Aptitude · Chapter: Ratio and Proportion · Exam: · Marks: · Difficulty:

If $A, B, C, D$ are quantities of the same kind such that $A: B=3: 4, B: C=5: 7$ and $C: D=8: 9$, find (a) $A: C$ (b) $B: D$ (c) $A: D$ (d) $A: B: C: D$

Answer

SELF-PRACTICE — the source book printed no answer.

Nothing is invented here, so this question has no answer on record.

Explanation

(a) $A:C = \frac{A}{C} = \frac{A}{B} \times \frac{B}{C} = \frac{3}{4} \times \frac{5}{7} = \frac{15}{28} = 15:28$. (b) $B:D = \frac{B}{D} = \frac{B}{C} \times \frac{C}{D} = \frac{5}{7} \times \frac{8}{9} = \frac{40}{63} = 40:63$. (c) $A:D = \frac{A}{D} = \frac{A}{B} \times \frac{B}{C} \times \frac{C}{D} = \frac{3}{4} \times \frac{5}{7} \times \frac{8}{9} = \frac{10}{21} = 10:21$. (d) Combining $A:B = 3:4$, $B:C = 5:7$ and $C:D = 8:9$ to a common scale gives $A:B:C:D = 30:40:56:63$.

Explanation as extracted from the printed page; notation may be imperfect.

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