Question

An alloy of 800 grams contains lead and tin in the ratio of 5 : 3. Find the quantity of tin is to be added to the mixture so the ratio of lead and tin will be 4: 5?

1. 400 gram
2. 225 gram
3. 300 gram
4. 325 gram

Answer 1

Correct Answer - Option 4 : 325 gram

Given:

Initially weight of alloy of lead and tin = 800 grams

Initially ratio of lead and tin in the alloy =  5 : 3

Finial ratio of lead and tin in the alloy = 4 : 5

Calculation:

Let the amount of tin added be x grams

Initially weight of lead in the alloy = 5/8 × 800 grams

⇒ 500 grams

Initially weight of tin in the alloy = 3/8 × 800 grams 

⇒ 300 grams

In final mixture lead will be same as initial 

⇒ 500/(300 + x) = 4/5

⇒ 2500 = 1200 + 4x

⇒ 4x = 1300 grams

⇒ x = 1300/4 grams 

⇒ x = 325 grams

∴ 325 grams of tin is to be added to the mixture so the ratio of lead and tin will be 4 : 5