Questions & Answers

Question

Answers

A.432

B.436

C.425

D.438

Answer
Verified

Step 1: There are three process in the above problem

Process 1:Removing 100 l milk and adding 100 l water

Process 2: Removing 200 l solution ( milk and water) and adding 200 l water

Process 3: Removing 400 l solution (milk and water) and adding 400 l water

Step 2: Before any process there is 1000 l of milk in the pot

By process 1 we removed 100 l of milk and added 100 l of water

Therefore the solution contains 900 l milk and 100 l water

From this the ratio of milk to water is given by

$

\Rightarrow 900:100 \\

\Rightarrow 9:1 \\

$

(we need to remember that there are totally 10 parts)

Step 3:

In the second process 200 l of solution is removed and 200 l of water is added.

Therefore , out of 200 l of solution that is to be removed 9 parts will be milk and 1 part will be water.

Milk removed =$200*\dfrac{9}{{10}} = 180l$

Water removed =$200*\dfrac{1}{{10}} = 20l$

After process 1 we had 900 l of milk and 100 l of water.

And now , amount of milk = 900 – 180 =720 l

amount of water=100 – 20 +200 =280 l(the 200 l of water was added in process 2)

So now the ratio of milk to water is given by

$

\Rightarrow 720:280 \\

\Rightarrow 36:14 \\

\Rightarrow 18:7 \\

$

(here we have totally 25 parts)

Step 4

In the third process 400 l of solution is removed and 400 l of water is added.

Therefore , out of 400 l of solution that is to be removed 18 parts will be milk and 7 parts will be water.

Milk removed =$400*\dfrac{{18}}{{25}} = 288l$

Water removed =$400*\dfrac{7}{{25}} = 112l$

After process 2 we had 720 l of milk and 280 l of water.

And now , amount of milk = 720 – 288 =432 l

Amount of water=280 – 112 +400 =568 l(the 400 l of water was added in process 3)

There the amount of milk at the end is 432 l

2.While finding ratio we need to make sure both the quantities are of the same units. If one quantity is in litre and another is in millilitre then we have to convert both to either litre or millilitre.