Question

Kevin, can clean a stadium in 5 hours working alone. Chris, can

Answer 1

Answer: It will about 1.88 hours or 1 hour 52.5 minutes to clean the stadium if they work together .

Step-by-step explanation:

Given : Time taken by Kevin to clean a stadium = 5 hours

Rate of work done by Kelvin =$\dfrac{1}{5}$

Time taken by Chris to clean a stadium  = 3 hours

Rate of work done by Chris =$\dfrac{1}{3}$

Let t be the time taken by both of them to clean the stadium together.

According to the question , we have

Rate of work done together = Rate of work done by Kelvin+Rate of work done by Chris

$\dfrac{1}{t}=\dfrac{1}{5}+\dfrac{1}{3}\\\\ \Rightarrow\ \dfrac{1}{t}=\dfrac{3+5}{15}\\\\ \Rightarrow\ \dfrac{1}{t}=\dfrac{8}{15}\\\\\Rightarrow\ t=\dfrac{15}{8} =1.875$

$t=1+0.875$ hours

$t=1\text{ hour }+0.875(60)\text{ minutes}$  [∵ 1 hour = 60 minutes]

$t=1\text{ hour }+52.5\text{ minutes}= \text{1 hour 52.5 minutes}$

Hence, It will about 1.88 hours or 1 hour 52.5 minutes to clean the stadium if they work together .