Question

$x:2a46b$

$y:1025c3045$

$z:90def20$ $x,y,z$ are proportional to each other. Find the value of $e-f$

• A. $15$
• B. $12$
• C. $18$
• D. $27$

Answer 1

Answer: (A)

$15$

$\frac{x}{y}=\frac{2}{10}=\frac{6}{30}=\frac{1}{5}=constant\Rightarrow x\propto y$

$y\times z=10\times 90=45\times 20=900=constant\Rightarrow y\propto \frac{1}{z}$

$x\propto y$ and $y\propto \frac{1}{z}\Rightarrow x\propto \frac{1}{z}$

$\Rightarrow a=\frac{25}{5},c=4\times 5=20,b=\frac{45}{5}=9$

$2\times 90=4\times 4=6\times f=b\times 20=180$

$\Rightarrow e=45,f=\frac{180}{6}=30,b=\frac{180}{20}=9$
$10\times 90=25\times d=900$

$e-f=45-30=15$