Question

In 50 kg mixture of sand and cement 45 is cement, how much sand should be added so that the proportion of cement is 10%

Answer 1

From the question:

Mass of cement = 45 kg
Mass of sand = 50 - 45 = 5 kg

Let the mass of sand to be added = x kg

The total mass of the mixture = (50 + x) kg

The proportion of cement here is 10%

⇒ 45/ (50 + x) x 100 = 10%

45/(50 + x) = 1/10
450 = 50 + x
x = 400

⇒ 400 kg of sand need to be added so that the proportion of cement can be 10%

Answer 2

weight of cement in mixture = 45 Kg
weight of sand in the mixture = 5 kg

Let x Kg sand should be added so that the proportion of cement will be 10%
so, final weight of sand in mixture = (x + 5) Kg
weight of mixture = 45 + (x + 5) = (x + 50) Kg
Now, proportion of cement in mixture in % = 10%
weight of cement in mixture/weight of sand in mixture = 10%
45/(x + 50) × 100 = 10
45/(x + 50) = 1/10
450 = x + 50 ⇒ x = 400

Hence, we should added 400 Kg sand in the mixture so that proportional of cement will be 10%