Proportions

[danny2335]

It takes melvin 3/10 of an hour to run 3/4 of a 5 kilometer race. If melvin runs at this same pace, how long, in hours, would it take him to run 10 kilometers?

A. 2/5
B. 3/5
C. 4/5
D. 5/2

Any ideas and what did you get as an answer?

Completely stuck on this problem?

 

[MarkFL]

Hello, and welcome to FMH!

Did you try something like this?

[MATH]\frac{\dfrac{3}{10}}{\dfrac{3}{4}\cdot5}=\frac{t}{10}[/MATH]

 

[Paul Belino]

First how far did Melvin run? It was (3/4) * 5 = 15/4 Km (Think of the word 'of' as multiply)
It took him 3/10 of an hour to run that.
Now for the next part we need to know how long it takes him to run 1Km in other words 10/10 of an hour.
We know he did 15/4 Km in 3/10 of an hour so the time to run 1Km is (10/3)*(15/4)
So from that you can work out the time taken for any distance

 

[danny2335]

Great thank you. I will look into both models.