Percent solution math; Please help!

[essay899]

Percent solution math; Please help! Please help with answer and explanation.

How many ml of a 20% solution should be added to 50 ml of 40% solution to obtain a 2%% solution?

Thanks You!

[pharmatiffany]

Hi,
There's a technique to solve this kind of exercise : See file attached.
Otherwise, do you have manan shroff calculation book ? It could be very useful for you if you have problems with solving these exercises. I really advise you this book, it makes calculations very comprehensible.

[mmachtin]

Something is wrong with the data in the question.
If one solution is 20% and the other is 40% the result of all the possible mixtures will be between 20% and 40%. It will never get lower than 20% and surely not 2%.
If you accidentally hit the "shift" key and It should be 25% then the answer is:

20 ...................15

........... 25

40......................5

you......desired.....parts
have

The calculations are in the diagonals.
|40 - 25| = 15 (parts of 20%)
|20 - 25| = 5 (parts of 40%)
Now, if 5 parts are 50 ml then 15 parts are 150 ml so the answer is 150 ml of 20%