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