Discussion Forum



1)

If $a:b=5:9$ and $b:c=4:7$, find $a:b:c$.


A) $30:36:63$

B) $20:36:63$

C) $10:36:15$

D) $20:55:35$

E) $10:42:12$

Answer:

Option B

Explanation:

$a:b=5:9$ and $b:c= 4:7$

$b:c$ $=\left(4\times\frac{9}{4}\right):\left(7\times\frac{9}{4}\right)$ $=9:\left(\frac{63}{4}\right)$

$a:b:c =5:9:\left(\frac{63}{4}\right)$ $= 20:36:63$.