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Sam is driving from Chicago to San Francisco, a distance of 2220 miles.
He covers the first 192 miles in 4 hrs. At this rate, how long will the entire trip take?
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I will show you two ways to solve this simple problem.
One way is using the rate; another way is using proportion.
1. Using the rate
The rate is the distance divided by the time: = 48 miles per hour.
Now the total time to cover 2220 miles at this rate is the distance divided by the rate:
total time = = 46.25 hours = 46 hours = 46 hours and 15 minutes. ANSWER
At this post, this solution is complete.
2. Using proportion
The rate is the same. Hence, we can write this proportion
= ,
where x is the unknown time.
From this proportion, you find x
x = = 46.25 hours = 46 hours = 46 hours and 15 minutes,
giving the same answer.
Thus the problem is solved in two ways for your better understanding.
Notice, that in proportion, each its side represents the rate, which is assumed the same
in both cases of partial distance and whole distance.