Question 635338
David participates in a bicycle race in which a rider starts every 5 minutes.
 David's average is 33 km/hr.
 After 28 minutes, he is overtaken by a rider who started 2 persons after him. What is the rate of the other cyclist in km/hr?
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Let s = speed of the 2nd cyclist
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From the information given, the 2nd rider started 15 min behind David
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Change 28 min to hrs: {{{28/60}}} hrs, David's travel time
Change (28-15) = {{{13/60}}} hrs, 2nd rider's travel time
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When this happens, they will have traveled the same distance.
Write a distance equation; dist = speed * time
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{{{13/60}}}s = {{{28/60}}}(33)
multiply both sides by 60
13s = 28(33)
13s = 924
s = 924/13
s = 71.1 km/hr, speed of the 2nd rider
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Confirm this by finding the distance of each
{{{13/60}}}*71.1 = 15.4 km
{{{28/60}}}*33 = 15.4 km