Question

Plz help me solve this question it's says the answer is 40cm^3
but I don't how do get it. plz it step by step​

Answer 1

Correct Question :-

▪ A jar contains 100 cm³ 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 oil must be added to make the ratio of oil to water 1 : 2.

Given :-

▪ A jar contains 100 cm³ of a mixture of oil and water which is in the ratio 1 : 4.

To Find :-

▪ Amount of oil which must be added to make the ratio of oil and water 1 : 2.

Solution :-

Let x amount of oil be added to the mixture.

first let us find the amount of water first,

⇒ Ratio before adding oil = 1/4

Let the common factor be y. we have

⇒ y + 4y = 100

⇒ 5y = 100

⇒ y = 20

∴ Amount of water = 80 cm³

Also,

⇒ Amount of oil = 20 cm³

Now, after adding the oil, the ratio becomes 1/2 but the amount of water would be constant, so we have

Ratio we have now,

⇒ (Amount of oil + added amount) / amount of water = 1 / 2

⇒ (20 + x) / 80 = 1/2

⇒ 20 + x = 40

⇒ x = 20 cm³

Hence, 20 cm³ of oil must be added.