if it takes a man 5 minutes to drive 10 miles how long will it take him to drive 12 miles?

Question

If it takes a man 5 minutes to drive 10 miles how long will it take the man to drive 12 miles? 

Answer 1

When you think of speed we think miles per hour or miles/hour.

So the units (labels) tell you to divide miles by hours  or  distance divided by time.

Here we have miles and minutes.

 

Divide the 10 miles by 5 minutes and you will get how fast you were going in miles/min.

 

Now you need to figure out how long (time) to go 12 miles (distance).

 

If you know miles/minute (distance/time) and miles (distance) what operation can you do to get just minutes.

Can you see that if you multiply (distance/time) X (time)  you will get  (distance)?

It is like  66/42 X 42 = 66.  (the 42's cancel out)

So that won't work you want time not distance.

 

What if you multiply (distance/time) X (1/distance) you will get (distance)?

It would be  like  66/42 X 1/66 = 1/42  (the 42's cancel out.

Not quite you are getting 1/time.

 

What about  distance divided by distance/time?

Hmmm - sounds good.  You flipped it over so now you get time and not 1/time.

 

Try that - divide 12 miles by  the miles/minute !!

 

So I hope I showed you how you can use the units to decide what to do.