Question

Two pipes can fill an empty tank in 20 hrs. And 30 hrs. Respectively. Find the time taken to fill the tank if both the pipes are opened simultaneously?

Answer 1

1st Pipe can Fill Tank in =20 hours

1st Pipe 1 hour Work=$\frac{1}{20}$

2nd Pipe can Fill Tank in=30 hours

2nd pipe 1 hour Work=$\frac{1}{30}$

If They Open Together their 1 hour Work.

$\frac{1}{20} + \frac{1}{30} \\ \\ = \frac{3 \times 1 + 2 \times 1}{60} \: \: \: \: \: (lcm = 60) \\ \\ = \frac{\cancel5}{\cancel{60} } \\ \\ = \frac{1}{12}$

Total hour=12

Point to be note 1 (hour or day)=1/hour or day

If any two Add Together like this

Answer will come=1/hour or day

So in Above its come =1/12

Total Time=12 hours.

$\boxed{\mathtt{\huge{Total\:Time=12\:Hours}}}$