An ore contains 18.8% of the mineral molybdenite, MoS2, which is a source of the element Mo. How much ore must be processed in order to obtain 12.0kg of Mo?

I seriously have no idea how to figure this out!!!! HELP

Question

An ore contains 18.8% of the mineral molybdenite, MoS2, which is a source of the element Mo. How much ore must be processed in order to obtain 12.0kg of Mo? 

I seriously have no idea how to figure this out!!!! HELP

anonymous · Answer

18.8% by weight means that of every 100 kg of MoS2, 18.8 kg are Mo.  Does that help?

If not...start with this question: there are 18.8 kg of Mo in every 100 kg of MoS2.  You want 12 kg of Mo.  Will you need more or less than 100 kg of MoS2 to get it?  How do you know?

anonymous · Answer

Then try this question: suppose you needed 9.4 kg of Mo (which is 50% of 18.8 kg).   How much MoS2 would you need?

What if you needed 40% of 18.8 kg?  What if you needed whatever percent 12 is of 18.8?