I've been refreshing myself on speed, distance & time calculations. But there is one question that's really bugging me:

What speed covers 12 miles in 1 hour 20 minutes?

Now I know that the answer is 9mph because I googled it but even with the answer in front of me I cant work out how to get to 9??

I know this is probably really easy but I haven't done any maths like this 7-8 years! Its non calculator and I need to know the break down of the calculation not just Speed = Distance/Time because 12/80(mins) = 0.15

Thanks for the help
12 miles in 80 minutes.

80/60 = 1.33 hours

12 miles /1.33 hours = approximately nine miles per hour.
12 miles
-----------
1.333 hours

=

x miles
------------
1 hour

Simplify.
ok but how did you get 1.33?
Quote by peterm85
ok but how did you get 1.33?

1 hour and 20 minutes is one and one third of an hour...
Quote by peterm85
ok but how did you get 1.33?

you divide 80 minutes (simplified from 1 hour & 20 minutes) by the number of minutes in an hour (60).
1 third of an hour
Maths dumb, just do drugs.
dude.....12/80=0.15 x 60 to get in mph..... which'll give you 9 mph
...of course!!! (not to the drugs comment lol), I knew it was going to be blindingly obvious!

cheers guys
ok.

80 minutes = 12 miles

to find how many miles per hour the easiest thing to do is to find out how far it travels in 60 minutes. To do this you have to find out how to get 60 minutes from 80 minutes.

60/80 = 0.75
0.75 x 80 = 60

So now we know that to get 80 to 60 we times by 0.75. Now we just do the same thing to the other side of the equation so it becomes:

80 minutes = 12 miles
80 x 0.75 = 12 x 0.75
60 minutes = 9 miles

And remember that
Time = Distance x Speed

Out of curiosity, what is this for?
Im going (hopefully) to Sandhurst, but my maths has always been ok, and I've got my Main Board in November so I want to get it up to scratch but like I said I haven't done Speed Distance Time since GCSE's. The question I asked was actually taken from a site designed for Royal Air Force Officer's training (OASC).
Counter question : why did you decide to ask UG rather than just like.. google it :\
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think about it like "x"mph x 4/3 miles = 12
rearrange and you get 12/(4/3) = x
so 36/4=9