Q. If A : B = 3 : 4, B : C = 5 : 7 and C : D = 8 : 9 then A : D is equal to
Answer: 10 : 21
Notes: $latex A : D = \frac{A}{D} = \frac{A}{B}\times \frac{B}{C}\times \frac{C}{D}&s=1$ $latex = \frac{3}{4}\times \frac{5}{7}\times \frac{8}{9}&s=1$ $latex => \frac{10}{21} = 10 : 21&s=1$ Hence option [A] is the right answer.

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