How many cups of 15% juice must be added up to 10 cups of 20% juice so the mixture in 17% juice?

Question

How many cups of 15% juice must be added up to 10 cups of 20% juice so the mixture in 17% juice?

Answer 1

Mahmut gave the standard answer. I will give a fun alternative.

Picture a seesaw. We have 10 at 20 3 to the right of 17 so how much do we need 2 to the lef?

Since the intervals are in the ratio 2:3, the juice is in the ratio 3:2

3/2 * 10 = 15.

Answer 2

Hello Sarang.

Lets say you need x cups of 15% juice. The formula should be:

x*15%+10*20% = (x+10)*17% (you can cancel percent on both sides)

15x +10*20 = (x+10)*17

15x +200 = 17x +170 (cancel 15x)

200 = 2x +170 (cancel 170)

30 = 2x (cancel 2)

15 = x

hope that helps