Question

Please help!

You need a 15% acid solution for a certain test, but your supplier only ships 5% solution and 17.5% solution. If you need 20 liters of 15% acid solution, how many liters of 5% and 17.5% solution do you need?

Answer 1

4 liters of 5% solution and 16 liters of 17.5% solution we need.

Explanation:

Let us assume that x liters of 5% solution and y liters of 17.5% solution are taken.

So, x + y = 20 ........ (1)

As the final solution is of 15%, so we can write

⇒ 5x + 17.5y = 300 ......... (2)

Now, solving equations (1) and (2) we get,

17.5y - 5y = 200

⇒ 12.5y = 200

⇒ y = 16 liters

Hence, x = 20 - y = 4 liters.

Therefore, 4 liters of 5% solution and 16 liters of 17.5% solution we need. (Answer)

Answer 2

4 liters of 5% solution and 16 liters of 17.5% solution we need.

Explanation:

Let us assume that x liters of 5% solution and y liters of 17.5% solution are taken.

So, x + y = 20 ........ (1)

As the final solution is of 15%, so we can write

`((5x)/(100)+ (17.5y)/(100))/(x + y) = (15)/(100)`

⇒ 5x + 17.5y = 300 ......... (2)

Now, solving equations (1) and (2) we get,

17.5y - 5y = 200

⇒ 12.5y = 200

⇒ y = 16 liters

Hence, x = 20 - y = 4 liters.

Therefore, 4 liters of 5% solution and 16 liters of 17.5% solution we need. (Answer)