Results 1 to 2 of 2

Math Help - speed and time problems

  1. #1
    Newbie
    Joined
    Jul 2005
    Posts
    3

    Question speed and time problems

    I'll quote the problem from my past papers...

    bernard and keith are having a race. bernard drives his car at an avarge speed of 200 km/h and keith at an avarage speed of 160 km/h

    after 1 1/2 hours bernard finishes the race

    (a) calculate the distance travelled by bernard in this time

    (b) how long does it take keith to finish the race?

    ... and also what is the "trick" of those problems ??
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Newbie Jamilworm's Avatar
    Joined
    Jul 2005
    From
    San Diego, CA
    Posts
    7
    Speed is a measure of distance in a certain time, or distance divided by time. With this, you can get an equation relating the three, like speed = distance/time. If you rearrange this equation, it can become distance = speed*time, or time = distance/speed.

    (a) calculate the distance travelled by bernard in this time
    You know speed and time, so you can plug them into the first equation to find distance, so:
    distance = 200*1.5 = 300km

    (b) how long does it take keith to finish the race?
    You now know distance and speed, so you can find time with the second equation:
    time = 300/160 = 1.875 hours

    You have to be careful when you use these equations, though, and make sure that the units of time and speed match up. Since the speed was km per hour, and our time was hours, we were ok.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: October 17th 2011, 02:50 PM
  2. Speed distance time problems
    Posted in the Algebra Forum
    Replies: 1
    Last Post: July 27th 2011, 11:14 AM
  3. Replies: 3
    Last Post: July 24th 2010, 02:32 AM
  4. Difficult Distance, Speed and time problems
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 22nd 2009, 03:52 AM
  5. Replies: 2
    Last Post: January 29th 2009, 03:38 AM

Search Tags


/mathhelpforum @mathhelpforum