Question

In one alloy, there is 50% steel in its total mass, while it is 75% in another alloy. 15 kg of the first alloy was melted together with 10 kg of the second one to form a third alloy. Find the percentage of steel in the new alloy when it is known that 20% of the total steel is getting diminished during the melting process?

1. 60%
2. 50%
3. 55%
4. 40%
5. 35%

Answer 1

Correct Answer - Option 3 : 55%

Given:

First Alloy = 15 kg

Second Alloy = 10 kg

Calculation:

Mass of steel in 1st alloy = 0.5 × 15

⇒ 7.5 kg.

Mass of steel in 2nd alloy = 0.75 × 10

⇒ 7.5 kg.

20% steel is reduced = 20% of the (7.5 + 7.5) kg

⇒ 0.20 × 15

⇒ 3 kg.

Remaining steel = 12 kg

Total alloy = 25 – 3

⇒ 22 kg

The required percentage of steel = (12/22) × 100 ≈ 55%

∴ The total steel is present in the third alloy is 55%.