Maths question

[tom]

If a car travels at a constant 80 mph how long does it take it to travel eight miles?

I can work this out using my basic arithmetic because I can see that eight miles is ten percent of the eighty miles travelled in an hour so it must take ten percent of 60 minutes so answer is six minutes.

But how do I work it out for 17 miles? Or 53 miles or whatever?

Is there a formula that you can put the different variables into and which makes it easy to work out using that?

I imagine that this is where algebra comes in which I could never get my head round.

 

[teaboy]

Speed = distance/time (Miles per Hour)
Distance = speed x time
Time = distance/speed

 

[Seagull over NZ]

Distance/MPH * 60 mins = number of minutes it will take.

 

[SeagullSongs]

Distance/Speed = Time.

Make sure you use the right units though. 8 miles divided by 80 miles per hour gives you 0.1 hours.
8 kilometers divided by 80 kilometers per hour gives you 0.1 hours too.

100 metres divided by 20 metres per second gives you 5 seconds.

To convert hours to minutes, multiply by 60.

 

[Shy Talk]

Are you in the middle of an exam?

 

[Seagull27]

Doing it your way, by saying that you can see 8 miles is ten percent of 80mph, so must be 10 percent of 60 minutes = 6 minutes:

To find how long for 17 miles, work out what percentage 17 is of 80: 17/80 * 100 = 21.25%

Then 21.25% of 60 minutes = 12.75 minutes.

 

[Mtoto]

Doing it your way, by saying that you can see 8 miles is ten percent of 80mph, so must be 10 percent of 60 minutes = 6 minutes:

To find how long for 17 miles, work out what percentage 17 is of 80: 17/80 * 100 = 21.25%

Then 21.25% of 60 minutes = 12.75 minutes.

How long does it take to travel 1 mile? 60/80, or 3/4 of a minute.

Then multiply by the number of miles.

 

[smeariestbat]

if a car travels that quickly on a uk road, it is breaking the speed limit and may get pulled over by the police. Thus lengthening the time it may take you to complete said number of miles.

 

[The Antikythera Mechanism]

That's not even an 11 plus question

 

[tom]

Thanks everyone for these responses. I think Seagul over NZ's:

Distance/MPH * 60 mins
= number of minutes it will take.

is the formula I am looking for. However I still dont 'see' what needs to be multiplied together and what needs to be divided into or by.

Especially as by playing around with the above formula it seems that:

Distance * 60 mins / MPH

Also works but:

Distance/60 mins * MPH

Or

MPH/Distance * 60 mins

Doesn't work.

I just don't 'see' what needs to be multiplied together or what needs to be divided by what.

I guess you either have a 'mathematics' head or as in my case, just an 'arithmetic' head.

Which probably means I'll just continue to find a bodge to get the answer to any other similar type of question.

Or just ask the nice people on this forum who have the right type of heads for the answer ;-)

P.s. and no I'm not sitting an exam in any of this, 11 plus or otherwise.

 

[Dunk]

Time is, as everyone has said, distance/speed.

Assuming you use miles and mph as units, your answer will be in hours.

To convert this to minutes, multiply the answer by 60.

So:

Time in minutes = (Distance/speed) x 60

or

(Distance x 60) / speed.

I think it is only confusing as there are 60 minutes in an hour. Once you get your head around that 1.3 hours is the same 78 minutes (1.3 x 60 = 78) and so on you are there.

Apologies if this is patronising.

 

[Shropshire Seagull]

80 MPH is too fast, you should not be driving at that speed.
If you have an accident, you may never arrive at your destination.