Jump to content


Welcome to BrainDen.com - Brain Teasers Forum

Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.

Of course, you can also enjoy our collection of amazing optical illusions and cool math games.

If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.

Thanks and enjoy the Den :-)
Guest Message by DevFuse
 

Photo
- - - - -

Speeding up


  • This topic is locked This topic is locked
159 replies to this topic

#61 Powerhouse

Powerhouse

    Newbie

  • Members
  • Pip
  • 6 posts

Posted 09 August 2007 - 08:44 PM

While there is nothing in the problem that states you have to travel directly to town there are many things that imply the question means you travel directly to town.

As far as the 2 answers go they are really the same answer. If you understand that you cant travel a distance of 30km in one hour and have your average speed be 60 km/hr after having traveled only 60 km then you understand the problem and that really is the main objective. However saying that people who say it is impossible are stupid and saying people who say it is possible if you dont travel straight to town are smart and creative thinkers does not make sense to me.

People who answered it is impossible say "it is impossible" and leave it at that. They understand that traveling off path would make it possible to reach a speed of 60 km/hr.
Do you really think saying you travel further is "thinking outside of the box", or do you think it is ignoring the assumptions the problem is trying to make you follow.

The reasons for the assumptions in my opinion are:
1. "If I go halfway to Town"-implies he is halfway there.
2. "to go the rest of the way"-because it says the way
3. "How fast do I have to go"-It is asking you for a speed, not for a speed and a distance.

While the 2 answers are correct the first answer is the simplest and in my opinion what they are looking for, at least the way they have worded this question.

You can pick apart almost any question if you spend enough time.
  • 0

#62 rubarb1

rubarb1

    Newbie

  • Members
  • Pip
  • 4 posts

Posted 15 August 2007 - 10:19 PM

If I have ever in my life claimed to be either smart or creative, I have certainly never claimed to be both at the same time.

These Logic problems/ riddles are full of loop holes. If these problems were simple and straight foward then the forums trying to answer them would not be so lengthy (7 pages for instance). Nor would they be as fun to read and take part in.

The intention of my answer was not to be "smart and creative" or to "think outside the box". I was just pointing out one of the many loop holes in this particular problem. The loop hole I gave was even hinted at in the author's solution, so I can't even claim it as my own.

I was also not calling anyone stupid, and to imply that I was is an unfair accusation. Frankly, everyone here is much smarter than I am. I agree that "impossible" is the most accurate answer to this problem. I just don't agree that it is the only possible answer. As you said, the two solutions are essentially the same thing.

Thanks for listening
  • 0

#63 Powerhouse

Powerhouse

    Newbie

  • Members
  • Pip
  • 6 posts

Posted 16 August 2007 - 01:34 PM

Not to get tons more posts but i never was saying "rubarb1" was calling people who said impossible un-creative and such but if you read previous people have said things like that and others.
  • 0

#64 rubarb1

rubarb1

    Newbie

  • Members
  • Pip
  • 4 posts

Posted 16 August 2007 - 05:12 PM

I read all the posts before replying. I understand that you weren't refering to just me, but I was included in the group you were refering to. I can't speak for the others, so I just spoke for myself. Sorry if it sounded too personal. Just throwing my two cents in that is all. No hard feelings.
  • 0

#65 PMitra

PMitra

    Newbie

  • Members
  • Pip
  • 6 posts

Posted 03 September 2007 - 12:49 PM

Impossible. One can do this only if He/She could stop time.....
  • 0

#66 walkingagh

walkingagh

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 07 September 2007 - 11:00 PM

Star Trek anyone? Beam me up, Scotty!
  • 0

#67 ifollohim

ifollohim

    Newbie

  • Members
  • Pip
  • 9 posts

Posted 08 September 2007 - 01:26 AM

I know how the people who don't get the elaborative math language feel.
I'm only in middle school.?
but either way I think I can explain this problem at an easier level than some others.

the distance is 60 km
you want your average to be 60 km per hour
if you did that from the start you'd get there In 1 HOUR
thats where The time limit 1 hour came from.
but if u traveled @ 30 km per hour you've used up your 1 hour when u got half way there
thus even if u went at infinant speed u would never reach the average of 60 km


And for every one else I told my dad this one and he got it but then told me to make an equation for it
All I knew was the equation of D=R*T
and I answered
60km= (30km)*(30km per hour)+(30km)*(t)
....(ignore these dots)........ 2

and I'm just a middle schooler that just learned D=R*T a few weeks ago!

and he joked that in order to reach 60km per hour u'd go !/@ of infinity
  • 0

#68 bluecrow

bluecrow

    Newbie

  • Members
  • Pip
  • 1 posts

Posted 10 September 2007 - 11:09 PM

where in the question does it say the whole journey must only take one hour?

if you do the first half at 30km per hour and the second half at 90km per hour then the average is 6okm/per hour over 2 hours
  • 0

#69 iknowall

iknowall

    Newbie

  • Members
  • Pip
  • 7 posts

Posted 13 September 2007 - 06:23 AM

[quote="rookie1ja"]Speeding up - Back to the Logic Puzzles
If I go halfway to the town (which is 60 km away) at the speed of 30 km/hour, how fast do I have to go for the rest of the way to have the average speed of the entire way 60 km/hour?

Edit: "rest of the way" means to the town and not an inch farther and the total distance traveled has to be exactly 60 km (this is just to explain how I meant the riddle to be understood)

ok people just saying there is no time limit on the trip all it say is that it is 60 km away. No time at all just distance. And if u are taking a stright route there then its impossible to average 60km/h. Why?

because you would need to travel at 90 km/h for the next hour to average it out and u would pass the town.

starting point - - - - - -halfway traveling 30km/h - - - - - - town - - - - - - where u would end up if traveled at 90km/h to average it out


each - is equal to 5 km
  • 0

#70 cursednacho

cursednacho

    Newbie

  • Members
  • Pip
  • 5 posts

Posted 14 September 2007 - 03:06 AM

If I go halfway to the town (which is 60 km away) at the speed of 30 km/hour, how fast do I have to go for the rest of the way to have the average speed of the entire way 60 km/hour?

Edit: "rest of the way" means to the town and not an inch farther and the total distance traveled has to be exactly 60 km (this is just to explain how I meant the riddle to be understood)



60 km/hour means PER HOUR not IN ONE HOUR, but assuming that it meant 60km/hr in one hour...
Halfway would be 30 minutes, and you have driven 15 km. To get the rest of the way of 45km in 30 minutes you would need to drive 90km/hr which is a given speed.

You also don't need to travel for an hour to go a certain speed. If you go from your home to the corner store which is a mile away. Traveling at 60km/hr means you are going 60km/hr and it just means you will get to the corner store in 1 minute.

Now assuming that it meant 30km is halfway the answer does not change, because you don't need to travel the entire time at a given speed to have an average speed.
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users