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PostPosted: Thu Oct 13, 2011 2:43 pm 
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Joined: Sat May 28, 2011 2:26 pm
Posts: 10
Question from an independent school paper

Because she is sick in bed and has nothing better to do . Amy counts the number of buses which go past her house in every two minute period. She gets the following results.

Number of buses
    0 1 2 3 4 5 6
    Periods in which this number pass
      15 17 12 6 6 5 1

      i) How many buses did she count ?
      ii) How long, at least would this have take her ?
      iii) What is the most likely number of buses to pass Amy’s house in any two minute period?


      Thank you in advance :)


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      PostPosted: Thu Oct 13, 2011 4:10 pm 
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      Joined: Sun Oct 31, 2010 7:43 am
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      a) how many buses did she count?

      Add busses in each period.

      0x15=0
      +
      1x17=17
      +
      2x12=24
      +
      3x6=18
      +
      4x6=24
      +
      5x5=25
      +
      6x1=6

      = 114 buses.

      How long would it have taken?
      = (Total number of periods) x (duration of each period)
      = (15+17+12+6+6+5+1) x (2 minutes)
      = 62 x 2
      = 124 minutes

      Most likely number of buses in any period?

      = 1 (because it happened 17 times)

      hope this helps.

      regards.


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      PostPosted: Thu Oct 13, 2011 4:10 pm 
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      Joined: Tue Jul 21, 2009 9:56 pm
      Posts: 8228
      Uh? I'm assuming the layout went wonky and the question is telling us that in 15 two minute periods 0 buses went past, in 17 2 minute periods 1 bus went past, in 12 2 minute periods 3 buses went past etc etc.

      So the number of buses she counted was 15x0 plus 17 x 1 plus 12 x 2 etc etc.

      How long, at least, did this take her - well each period was 2 minutes and she counted for 15+17+12+6+6+5+1 periods. Then multiply the number of periods by 2 minutes.

      Most likely number of buses to pass is 1, as this is the number that went past during 17 of the time periods, and 1 is the number that occurred most frequently as 17 is the highest number of periods to have the same number of buses passing.

      Hope that makes sense.


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      PostPosted: Thu Oct 13, 2011 4:11 pm 
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      Joined: Tue Jul 21, 2009 9:56 pm
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      Oops someone else replied at same time as me!!


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      PostPosted: Thu Oct 13, 2011 8:17 pm 
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      Joined: Sat May 28, 2011 2:26 pm
      Posts: 10
      Hello

      Thank you to both of you :) The tabulation didn't work out - sorry.


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