SOLUTION: It took Millie a total of 4 hours to drive 75 miles to airport and fly 2100 miles to a city in Mexico. If the plane rate is 12 times faster than her car, how fast did she drive?

Question 1151526: It took Millie a total of 4 hours to drive 75 miles to airport and fly 2100 miles to a city in Mexico. If the plane rate is 12 times faster than her car, how fast did she drive?
Found 2 solutions by greenestamps, Alan3354:
Answer by greenestamps(13203) (Show Source): You can put this solution on YOUR website!

12 times faster than the car? or 12 times AS FAST?

They mean different things, and of course the answers will be different....

If the car's speed is x, then "12 times AS FAST AS" the car is 12x.

If the car's speed is x, then "12 times FASTER THAN" the car is x, plus 12 more times x, or x+12x = 13x.

Unfortunately, in everyday usage the two phrases are used to mean the same thing.

Nearly always, when you see the phrase "x times faster than..." the intended meaning is "x times as fast as...".

In this problem, "12 times as fast as" gives a "nice" answer but "12 times faster than" does not. So we can assume the intended meaning is "12 times as fast as".

So....

Let x be the speed of the car; then the speed of the plane is 12x.

The time to drive 75 miles at x mph is 75/x; the time to fly 2100 miles at 12x mph is 2100/(12x).

The total time is 4 hours:

Multiply everything by 12x to clear the fractions:

You can finish from there....

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Then there's "3 times sooner" and "10 times smaller."

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