Question

A gardener is digging a plot of land, As he gets tired, he works more slowly. After 't' minutes he is digging at a rate of $\frac{2}{\sqrt{t}}$ square meters per minute. How long will it take him to dig an area of 40 square meters?

• A. 10 minute
• B. 400 minute
• C. 100 minute
• D. 30 minute

Answer 1

Answer: (B)

400 minute

Rate of work done $=\frac{2}{\sqrt{t}}$ square meter per minute

So total area digged in $t$ minute $=$ $rateofworkdone$ $\times$ $time\left(t\right)$

$\Rightarrow t\times \frac{2}{\sqrt{t}}=40$

$\Rightarrow \sqrt{t}=20$

$\therefore t={20}^2=400$ minute