It will melt to how many inches?

Question

Under typical conditions, 0.5 ft of snow will melt to 2 inches of water. To how many inches of water will 2.5 ft of snow will melt? 

Answer 1

Tyronglia, this is what we call a proportion problem, when two ratios are equal, like 1/2 = 3/6. We can either cross multiply, 1 x 6 = 2 x 3, or 1 x 3 = 3 and 2 x 3 = 6.

 

So, we have .5 ft snow/2 inches = 2.5 ft snow/? inches

 

.5 x what = 2.5? 5, right? 2 x 5 = 10, so 2.5 ft of snow makes 10 inches of water.

 

Hope this helps!

 

 

Answer 2

You can think of this problem two ways.  The first is as David has explained - a proportion problem.  The second is as real life common sense.

 

The problem says that 0.5 feet of snow melts to 2 inches, right?  But it's easier to understand that proportion if you change both sides to inches.  At 12 inches per foot, 0.5 feet is 6 inches, right?  

 

So, according to the problem, every 6 inches of snow melts to 2 inches of water, a proportion (there's that word again) of 3 to 1.  Every 3 inches of snow becomes 1 inch of water.

 

Well, how many inches is 2.5 feet?  2.5 times 12 is 30 inches of snow, which at 3 to 1 will melt to 10 inches of water. 

 

Now, the way I've explained it is, mathematically, EXACTLY the same solution as the one David explained above.  But, for some people, this way is easier to actually SEE, HEAR and FEEL the proportional relationship.  

 

Some teachers, for full credit, require the equation to be set up the way David showed you.  KNow your teacher, and do whatever they require for full credit.

 

The great thing is that, if you consider the problem in real life terms, you can be sure that, after you have solved the equation that you set up, that the solution you ended up with is reasonable in real life.