In one alloy there is 12% chromium while in another alloy it is 8%. 15 kg of the first alloy was melted together with 30 kg of the second one to form a third alloy. Find the percentage of chromium in the new alloy.
Select the correct option:
A) 9.4 % B) 9.33 % C) 9.6 % D) 9.8 % E) 10 %

Rationale: "the amount of chromium in the new 15 + 30 = 45 kg alloy is 0.12 * 15 + 0.08 * 30 = 4.2 kg , so the percentage is 4.2 / 45 * 100 = 9.33 % . answer : b ."
Answer: B