In what ratio must water be mixed with milk, costing ₹32 per litre, in order to get a mixture costing ₹28 per litre?

Question

Question

This question was previously asked in

SSC CGL 2023 Tier-I Official Paper (Held On: 14 Jul 2023 Shift 2)

Answer 1

Given:

We know that the cost of water = Rs. 0 per litre

Cost of milk = Rs. 32 per litre

Cost of mixture = Rs. 28 per litre

Formula used:

Cost of mixture = Total cost / Total quantity

Calculation:

Let the ratio of water and milk be "1 : a"

⇒ (1 × 0) + (a × 32) = (1 + a) × 28

⇒ 0 + 32a = 28 + 28a

⇒ 4a = 28

⇒ a = 7

Now, the ratio of water and milk is 1 : 7

Shortcut Trick

Now the ratio of water and milk is 1 : 7.