Question

David and his wife each receives $8$ percent annual rise. If David receives a raise of $\text{Rs.}800$ and his wife receives a raise of $\text{Rs.}840,$ then what is the difference between their annual income after their raises?

• A. $\text{Rs.}540$
• B. $\text{Rs.}740$
• C. $\text{Rs.}40$
• D. $\text{Rs.}560$

Answer 1

The correct option is A $\text{Rs.}540$

Let David's annual income be $\text{Rs.}x$ and his wife's annual income be $\text{Rs.}y$
Then, $8\%$ of $x=800$
$\Rightarrow \frac{8}{100}\times x=800$
$\Rightarrow x=\frac{800\times 100}{8}=10000$
And, $8\%$ of $y=840$
$\Rightarrow \frac{8}{100}\times y=840$
$\Rightarrow y=\frac{840\times 100}{8}=10500$
$\therefore$ Required difference
$=\text{Rs.}\left[\right(10500+840)-(10000+800\left)\right]=\text{Rs.}540$