A car travels 3/1000 of a mile in 1/200 of a minute. What is the car's speed?

Question

Trying to find the speed of the car.

Answer 1

You did not specify the unit of speed so there are many answers. With cars, you normally talk about miles per hour but you can convert this to feet per second, yards per minute....

 

First thing I would do is multiply both numbers by 200 which gives you 600/1000 of a mile in 1 minute. If you're talking about the rate miles per minute, reduce and you're done. So that would be .6 miles/min.

 

If you now want to convert to mph, also written miles/hr, you need to multiply by 60 min/hr to get your new answer of 36 miles/hr. IMPORTANT: Do you see how the rate unit changed? miles/min * min/hr = miles/hr, just like fractios, the min in the denominator cancels with the min in the numerator. In more complex problems, keeping track of your units like this is very important.

Answer 2

speed is distance divided by time

 

so divided your distance 3/1000 mile by your time 1/200 minute

 

remember dividing by a fraction 1/200 is the same as multiplying by the reciprocal 200/1