An alloy A contains two elements, copper and tin in the ratio of 2 ∶ 3, whereas an alloy B contains the same elements in the ratio of 3 ∶ 4. If 20 kg of alloy A, 28 kg of alloy B and some more pure copper are mixed to form a third alloy C which now contains copper and tin in the ratio of 6 ∶ 7, then what is the quantity of the pure copper mixed in the alloy C?
An alloy A contains two elements, copper and tin in the ratio of 2 ∶ 3, whereas an alloy B contains the same elements in the ratio of 3 ∶ 4. If 20 kg of alloy A, 28 kg of alloy B and some more pure copper are mixed to form a third alloy C which now contains copper and tin in the ratio of 6 ∶ 7, then what is the quantity of the pure copper mixed in the alloy C? Correct Answer 4 kg
GIVEN :
An alloy A contains two elements, copper and tin in the ratio of 2 ∶ 3
whereas an alloy B contains the same elements in the ratio of 3 ∶ 4
If 20 kg of alloy A, 28 kg of alloy B and some more pure copper are mixed to form a third alloy C which now contains copper and tin in the ratio of 6 ∶ 7
ASSUMPTION :
Let the amount of pure copper added be ‘x’ kg.
CALCULATION :
Amount of copper in 20 kg of alloy A = 2/ (2 + 3) × 20 = 8 kg
Amount of copper in 28 kg of alloy B = 3/ (3 + 4) × 28 = 12 kg
Total amount of copper in alloy C = 8 + 12 + x = 20 + x
Total amount of alloy C produced = 20 + 28 + x = 48 + x
⇒ 20 + x = 6/ (6 + 7) × (48 + x)
⇒ 20 + x = 6/13 × (48 + x)
⇒ 260 + 13x = 288 + 6x
⇒ 7x = 28
∴ x = 4 kg