a box can hold 36 cups or 24 jugs. If there are already 6 jugs and 19 cups in the box, how many more cups can Miss Lim put in the box?

Question

I know how to do this question in my own method...but I'm not sure what the right method is, plus I have to teach a student how to do this method soon! SOS

Any other methods??

Answer 1

First figure out how much space a cup and a jug each take up.

 

The box can hold 36 cups, so each cup takes up 1/36 of the box.  Similarly, a jug takes up 1/24 of the box.

 

If there are 6 jugs, that means the jugs are currently taking up 6/24 = 1/4 of the box.

 

And there are 19 cups, so the cups are taking up 19/36 of the box.

 

So altogether the cups and jugs already in the box are taking up 1/4 + 19/36 = 9/36 + 19/36 = 28/36 of the box.

 

Since each cup takes up 1/36 of the box, there is room for 8 more of them.  That would add up to 36/36, which is the whole box.