RIDDLE: Average Car Speed (Warning: Tricky!)

[Up_Tilt_390]

Just thought we'd all have a bit of forum fun with this very tricky riddle. I love doing this one, so here it is below...

There is a racecourse loop that, if laid out flat, would stretch exactly one mile. So there is basically a mile of racecourse track.

A driver does a whole lap around the racecourse, averaging a speed of 30mph. How fast would the car have to go on the second lap in order to average a speed of 60mph over the course of BOTH laps?

Enjoy getting your head wrapped around this one

 

[Bletchleyite]

Have an answer...shall I post?

 

[Up_Tilt_390]

Have an answer...shall I post?

If you so dare

 

[Bletchleyite]

I *think* it's 90. But could be wrong.

 

[Up_Tilt_390]

I *think* it's 90. But could be wrong.

Yes. I'm afraid that is the incorrect answer.

 

[Bletchleyite]

Yes. I'm afraid that is the incorrect answer.

I think I know why. Time to get a piece of paper out to work it out properly

 

[Bletchleyite]

OK so let's work this out.

1st lap of 1 mile at 30mph takes 1/30 hours which is 2 minutes.
2 laps, totalling 2 miles, at 60mph would take 2/60 hours which is also 2 minutes. So the second lap would have to take 0 minutes.

Therefore it's impossible (or infinite speed, if you prefer).

 

[Up_Tilt_390]

OK so let's work this out.

1st lap of 1 mile at 30mph takes 1/30 hours which is 2 minutes.
2 laps, totallng 2 miles, at 60mph would take 2/60 hours which is also 2 minutes. So the second lap would have to take 0 minutes.

Therefore it's impossible (or infinite speed, if you prefer).

Aww, I was hoping there'd be a bit more of a fuss over the answer Oh well, congratulations Bletchleyite

 

[Bletchleyite]

Aww, I was hoping there'd be a bit more of a fuss over the answer Oh well, congratulations Bletchleyite

I do like a challenge - needed a pen and paper to get there though!

 

[Up_Tilt_390]

I do like a challenge - needed a pen and paper to get there though!

Some challenge if it only took two attempts

 

[DaleCooper]

If the car could travel at the speed of light then to an observer in the car it would appear to take zero time to complete the second lap so the total time for that observer to complete two laps would be 2 minutes.

 

[Howardh]

While we're in the riddlesphere, here's my favourite.

York is only 70 miles from Russia, but anywhere in Wales is even closer.

Explain!

 

[Up_Tilt_390]

While we're in the riddlesphere, here's my favourite.

York is only 70 miles from Russia, but anywhere in Wales is even closer.

Explain!

Is it simply how Wales is closer to York than it is to Russia?

 

[AndyPJG]

While we're in the riddlesphere, here's my favourite.

York is only 70 miles from Russia, but anywhere in Wales is even closer.

Explain!

There's a 'Russia Hall' just SE of Chester?

 

[bonzawe]

try

https://en.wikipedia.org/wiki/York,_Alaska

and

https://en.wikipedia.org/wiki/Wales,_Alaska

 

[MotCO]

I do like these riddles. Any more?

 

[DarloRich]

Just thought we'd all have a bit of forum fun with this very tricky riddle. I love doing this one, so here it is below...

There is a racecourse loop that, if laid out flat, would stretch exactly one mile. So there is basically a mile of racecourse track.

A driver does a whole lap around the racecourse, averaging a speed of 30mph. How fast would the car have to go on the second lap in order to average a speed of 60mph over the course of BOTH laps?

Enjoy getting your head wrapped around this one

I don't know or care. I have always hated these "puzzles". stupid things. Fact I don't understand them and cant do them doesnt come into it.

 

[Up_Tilt_390]

I do like these riddles. Any more?

An easy one right here...

A man with two sheeps and a wolf comes to a river that he has to cross via a boat. He can only fit in ONE animal per boat ride, but if he leaves any sheep with the wolf unattended, then the wolf will eat it. How can he get across the river with all three animals?

 

[Up_Tilt_390]

I don't know or care. I have always hated these "puzzles". stupid things. Fact I don't understand them and cant do them doesnt come into it.

To each their own. If you really don't like it then just don't bother with this thread then. Would probably be ideal to un-watch it so it doesn't appear in your lists or what not.

 

[JoeGJ1984]

Take the wolf over
Return
Take one sheep over
Take the wolf back
Take the second sheep over
Return
Take the wolf over

(This is an old puzzle; the 'wolf, goat and cabbage' puzzle).

 

[Up_Tilt_390]

Take the wolf over
Return
Take one sheep over
Take the wolf back
Take the second sheep over
Return
Take the wolf over

(This is an old puzzle; the 'wolf, goat and cabbage' puzzle).

Well I guess I'm done with these riddles then

 

[Bayum]

I don't understand how it isn't 90mph...

 

[Up_Tilt_390]

I don't understand how it isn't 90mph...

Because if the car does the first mile at 30mph, that means it has taken two minutes. Doing it at 90mph in the second lap would take about 40 seconds. 2 minutes 40 seconds would be an average of about 45mph. There's sixty seconds in a minute, and 60 minutes in an hour. 60mph is a mile per minute, but the first lap was done at 30mph, so two minutes have already been used up. No matter how fast you go in the second lap, you will never average 60mph over the course of both laps.

 

[Bayum]

I assume it's been worked out via total distance driven as opposed to speed in that case?

 

[Up_Tilt_390]

I assume it's been worked out via total distance driven as opposed to speed in that case?

I can't quite explain it myself, I only know the answer through finding out myself and looking at some of the explanations.

 

[Howardh]

try

https://en.wikipedia.org/wiki/York,_Alaska

and

https://en.wikipedia.org/wiki/Wales,_Alaska

...in one.!

 

[thejuggler]

I assume it's been worked out via total distance driven as opposed to speed in that case?

Like a lot of riddles you need to analyse what is being asked. The question states an “average on BOTH laps”, not an average of 60 mph over 2 miles.

If one lap has already been completed its impossible to do it again to increase the average speed.

 

[pdeaves]

I assume it's been worked out via total distance driven as opposed to speed in that case?

As speed is a fraction (distance divided by time) it's converting everything to the same denominator (time). It's like 1/2 plus 1/3 is not 2/5, it is 5/6 (3/6 plus 2/6).

 

[DarloRich]

OK so let's work this out.

1st lap of 1 mile at 30mph takes 1/30 hours which is 2 minutes.
2 laps, totalling 2 miles, at 60mph would take 2/60 hours which is also 2 minutes. So the second lap would have to take 0 minutes.

Therefore it's impossible (or infinite speed, if you prefer).

that makes sense but i have no idea how you work that out from the information given. I could sit all week and never be able to understand it. My brain just doesnt work like that.

We had a question at school in a paper which was basically if train A leaves station A travelling at 100mph and train B leaves station B traveling towards train A at 60 mph where will they meet and after how long.

I put:
a) Northallerton.
b) depends on the timetable and any disruption.

Result =A telling off.

 

[AlterEgo]

We had a question at school in a paper which was basically if train A leaves station A travelling at 100mph and train B leaves station B traveling towards train A at 60 mph where will they meet and after how long.

I put:
a) Northallerton.
b) depends on the timetable and any disruption.

Result =A telling off.

An even smarter-arse answer would be "wherever the passing loop is, hopefully".