Maths Speed Problem

• kkhing

  15 Aug 09, 11:57

  

• rurumoo

  7 Oct 09, 17:12

  25km-20km=5km (every hour, Sam is 5km ahead of tom)

  In order for them to pass each other, they must have a distance of 2km between them.

  5/2 = 2.5

  2.5x60=24mins

  24 mins after starting point, they met.

  24mins = 2/5h

  2/5x25=10km

  10km/2km = 5 rounds

  a) Sam travelled 5 rounds.

  b) 24 mins

   

  I know A is correct, but i'm not sure for B ...

   

• hazelp

  8 Oct 09, 08:15

  the above calc is largely correct except for error in line 3 and 4 - typo error maybe cos final answer correct

  line 3 should be 2/5 instead of 5/2

  then 2/5 times 60 mins = 24 mins.

  the rest are fine. 

  in this case , the first time Sam overtakes Tom happens to be at A exactly, (since the number of rounds calculated is a whole number this means Sam is back at A)

  so the answer for (b) can be taken from the calculations for (a)