Travel Time Problem

[SCSmith]

Two cars start at the same location and travel in the same direction at average speeds of 30miles per hour and 45 miles per hour. How much time must elapse before the two cars are 5 miles apart?

Let t = the time that must elapse before the two cars are 5 miles apart.

30t + 45t = 5

75t = 5 Add like Terms

t= 5/75 or .33 mins.

Is this correct set up and solution?

These problems have no solutions in the back of the text.

 

[galactus]

No, it's not. 0.33 minutes. So, you're saying, in 20 seconds the cars will be 5 miles apart?. Think about it. Does that seem correct?.

Besides, 5/75 = 1/15 = 0.066667, not 0.33.

You're close, though. Try subtracting instead of adding.


\(\displaystyle \L\\45t-30t=5\)

Now, solve for t.

Remember, t will be in hours.