Question

A jar contains 100ml of a mixture of oil and water in the ratio 1:4. Enough oil is added to make the ratio of oil to water 1:2. How much water must be added to make the ratio oil to water 1:3?

Answer 1

• 40 ml of water must be added.

Explanation:

Initial volume of mixture is 100 ml with oil to water ratio of 1 : 4.

First, let's find the volume of each component.

If the oil is x then water is 4x according to ratio and their sum is 100 ml:

• x + 4x = 100
• 5x = 100
• x = 20

So, we have 20 ml of oil and 80 ml of water.

Now, let's added volume of oil be y. Then we have the ratio:

• (20 + y)/80 = 1/2
• 20 + y = 40
• y = 20

So, we have 40 ml of oil and 80 ml of water.

Lastly, let's added water be z. Then we have the ratio:

• 40/(80 + z) = 1/3
• 80 + z = 120
• z = 40

We must add 40 ml of water.