Word problem

Question

I can run 5 miles in one hour. At this rate, how long will it take me to run 7 miles? 

 

Step by Step

Answer 1

Hi,

Your rate is 5 miles/hr. Use a proportion to solve for the time it takes to run 7 miles or x.

 

5miles/hr = 7miles/x hrs

 

cross multiply and divide

 

x hrs (5 miles) = 1 hr (7 miles)

 

x hrs = 7/5 = 1 and 2/5 hrs or 1 hr and 2/5 hrs (60 minutes/1 hr) = 1 hr and 24 minutes

Answer 2

Step 1) running at a certain velocity is a rate of how far you traveled in a given amount of time.

 

Step 2) at that rate, the question is how long would it take to cover a new distance at the same speed.

 

Speed = 5 miles/ 1 hour

 

(7 miles)/(5 miles/1 hour) which, when simplified, becomes (7/5) hours = 1.4 hours or 74 minutes.

 

In terms of units, the (7 miles) term and the (5 miles/ 1 hour) term, the "miles" cancel and the "hour" term comes up to the numerator, thus giving 1.4 hours or 74 minutes.