Ratio Question 1 with Solutions

Yesterday I went over my method for setting up a ratio, and I gave you three ratio problems to try on your own. You can see that post here: Setting Up a Ratio

Today I would like to give a solution to the first of those three ratio problems. I will give solutions to the other two problems throughout this week.

Problem 1: Running at a constant speed, a cheetah traveled 200 miles in 5 hours. At this rate, how many miles did the cheetah travel in 4 hours?

Solution: As in yesterday’s problem we identify 2 key words. This time let’s choose “miles” and “hours.”

    miles           200      x
   hours             5       4

We now find x by cross multiplying and dividing.

200/5 = x/4
800 = 5x
x = 800/5 = 160.

Alternate solution: Using d = r ⋅ t (distance = rate ⋅ time), we have

200 = r ⋅ 5
r = 200/5 = 40 mph

Using d = r ⋅ t again, we have d = 40 ⋅ 4 = 160.

* Mental math: 200 miles in 5 hours is 40 miles per hour (divide 200 by 5).  Thus, the cheetah traveled 4 ⋅ 40 = 160 miles in 4 hours.

More Problems with Explanations

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