Question

A species of shark spends $25$% of a day, d, sleeping, and $50$% of the remaining time hunting. Which of the following expressions represents how many hours in one day are left for other activities?

• A. $\frac{d}{2}$
• B. $\frac{3d}{4}$
• C. $\frac{3d}{8}$
• D. $\frac{3d}{12}$

Answer 1

Answer: (C)

$\frac{3d}{8}$

Total time in one hours=$d$

$25\%$

of a day spends on sleeping

$\therefore$Time shark spend for sleeping=$\frac{25}{100}\times d=\frac{d}{4}$

Remaining time =$d-\frac{d}{4}=\frac{3d}{4}$

Shark spend $50\%$ of the remaining time for hunting

$\therefore$Time shark spend for hunting=$\frac{3d}{4}\times \frac{50}{100}=\frac{3d}{8}$

The hours left in one day for other activities=$d-(\frac{d}{4}+\frac{3d}{8})$

$\Rightarrow d-\left(\frac{2d+3d}{8}\right)$

$\Rightarrow d-\frac{5d}{8}$

$\Rightarrow \frac{8d-5d}{8}=\frac{3d}{8}$