Thread: unit conversion

I can't seem to figure this one out. Can someone explain?

The price of ground coffee beans is d dollars for 8 ounces and each ounce makes c cups of brewed coffee. In terms of c and d, what is the dollar cost of the gound coffee beans required to make 1 cup of brewed coffee?

A)

B)

C)

D)

E)

The correct answer is A.

In these kind of problems, it is best to set up ratios and you have to be careful with your units.

Price of ground coffee beans:

Ratio of ounces to cups:

==========================

Now I need to find the cost of the ground coffee beans required to make 1 cup of brewed coffee. So, what we do first, is convert 1 cup into oz using the ratio given:



Notice that the cup unit cancel (and don't leave the s behind! ):





Now, last thing to do is to multiply the converted unit with the price:


Again, the units cancel, leaving you with the price:

Ah, I see it thank you!