Aptitude - Alligation or Mixture - Discussion

I'm also confused.

How it is possible. Please explain.

Hope guys. This will help you.

40-4 == taken out 10% milk == 36.

36-4 == taken out 10% milk == 32.40.

32.40 == taken out 10% milk == 29.16.

Why is 3 taken as the power whereas it should be 2 as its repeated two times. Someone please explain?

40-4 == 36.

Now mixture contain 36 part milk and 4 part water.
36-4 = 32.

But all 4 part is not milk, it is mixture of water and milk.
In 4 part amount of water was=4*4/40=1*4/10=0.4.

So now milk = 32+0.4 = 32.4.

Process repeats one more time as follows:

Milk = 32.4-4 = 28.4.
This 4 is mixture of water and milk.
Water in this 4 lit is = 7.6*4/40 = 0.76.

So finally milk = 28.4+0.76 = 29.16.

40 lit milk.
4 lit taken out.

36 lit milk and 4 lit water.
Again 4 lit mixture remove from total mixture.

4/ (total mixture = 40) --- 1 eqn.

36*4/40 = 3.6 milk and 4*4/40 = 0.4 water are remove.

Remaining milk = 32.4 (36-3.6) and water = 7.6 (8-0.4) lit.

Again same process as equation (1).

32.40-3.24 = 29.16 lit milk remains in mixture.

Simplest approach. !

First the milk had removed and replace by water it is 1 time later it had repeated for 2 times.

So total 1+2 = 3 times.

So the value of n is taken as 3.

It has given repeated twice, so three is taken as a power? Still not getting.

For this type of questions the formula is a(1-b/a) whole power n.

a = Initial quantity.
b = Taken out quantity.
n = Nor of times.

If the same amount of milk is drawn the formula is applicable but when different amounts of milk is drawn in different cases what have to do I have a problem here please solve this and explain.

There was 40 litres of pure milk in a vessel 16 litres of pure milk was taken out and replaced with equal amount of water again 10 litres of mixture was taken out and replaced with equal amount of water, what is the amount of water in the vessel now? (in litres).