Question

It is known that a : b , c : d and e : f are in proportion, which of the following is/are true ?

• A. ac = bd
• B. ab = cd
• C. af = eb
• D. cf = ed

Answer 1

Answer: (C), (D)

The correct options are
C af = eb
D cf = ed

$\because$ a : b , c : d and e : f are in proportion.

$\therefore$ $\frac{a}{b}=\frac{c}{d}=\frac{e}{f}$

Taking the first two ratios, we have,

$\frac{a}{b}=\frac{c}{d}$

$\Rightarrow$ ad = bc

Taking the first and the last ratio, we have,

$\frac{a}{b}=\frac{e}{f}$

$\Rightarrow$ af = eb

Taking the second and the last ratio, we have,

$\frac{c}{d}=\frac{e}{f}$

$\Rightarrow$ cf = ed

It can be seen only options (c) and (d) are true.