Question

Two pipes a and b can fill a tank in 20 and 30 minutes respectively if both the pipes are used together then how long will it take to fill the tab

Answer 1

$\textbf {Hey there, here is the solution.}$

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STEP 1: Find the rate:

Pipe A can fill the tank in 20 mins

Rate = 1/20 tank/min

Pipe B can fill the tank in 30 mins

Rate = 1/30 tank/min

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STEP 2: Find the rate if both work together:

If Pipe A and Pipe B are used together,

I min = 1/20 + 1/30 = 1/12

Rate = 1/12 tank/min

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STEP 3: Find the number of mins needed:

1/12 tank = 1 min

12/12 tank = 1 x 12 = 12 mins

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Answer: It will take 12 minutes to fill up the tank.

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$\textbf {Cheers.}$

Answer 2

Pipe $\bf{a}$ can fill the tank in $\bf{20}$ minutes

Pipe $\bf{a}$ = $\red{1/20}$ tank/min

Pipe $\bf{b}$ can fill the tank in $\bf{30}$ minutes

Pipe $\bf{b}$ = $\green{1/30}$ tank/min

Now,
If both pipes will fill the tank together,
So, the rate of both pipes working together :

➡ $\red{1/20}$ + $\green{1/30 }$

➡ $\red{5/60}$ = $\green{1/12 }$

= $\bf{1/12 }$tank/min

Therefore,

1/12 tank = 1 minute

1 tank = 1 × 12 = 12 minutes

Hence,
$\bf{It \: \: will\: \: take\: \: 12 \: \:minutes \: \:for\: \: both \: \:the\: \: pipes\: \: working \: \:together \: \:to\: \: fill \: \:the\: \: tank. }$