2. Two cyclists start biking from a trail's start 3 hours apart. The second cyclist travels at 10 miles per hour and starts 3 hours after the first cyclist who is traveling at 6 miles per hour. How much time will pass before the second cyclist catches up with the first from the time the second cyclist started biking? A. 2 hours B. 4 ½ hours C. 5 ¾ hours D. 6 hours E. 7 ½ hours
4 1/2 hours
how?
can u draw it 4 me?
the 1st cyclist travels @ 6mph and started 3 hours earlier than 2nd cyclist hence already travelled 18 miles .. Hours Miles traveled 3 18 miles (1st) 0 miles (2nd) -- 2nd starts @ 10mph after 3 hrs 4 24 10 5 30 20 6 36 30 7 42 40 7.5 45 45 -- hence 7.5 hrs - 3 hrs = 4.5 hrs
why did u subtract -3 at the end?
?
since it was from the time the second started biking
the question was from the time the second one started cycling so he did it 3 hrs later to 1st cyclist
but we gave the first biker a head start by 3 and the second biker at 0
Here is one way to think about it. the first biker goes 3 hr * 6 m/hr = 18 m in 3 hours now we start the clock. the first biker will be 18+6t away where t is the time in hours meanwhile the second biker has started, and he goes 10t in t hours after a certain amount of time we expect 10t = 18+6t (they have traveled exactly the same distance. that means the 2nd biker has caught up to the 1st biker) solve for t
1st cyclist: head start - 3hrs so travel advantage of 18 miles as he was travelling @ 6mph so after 1st hr with reference to the 2nd cyclist 1st cyclist traveled 24 miles ( 18 miles for head start + 6mph -his normal speed ) 2nd cyclist @ 10 mph - 10 miles so after 4.5 hrs both traveled 45 miles ( 1st cyclist = 18 miles head start + 6 miles for 1st hr + 6 miles for 2nd hr + 6 miles for 3 hr + 6 miles for 4th hr + 3 miles for half an hour ) and also 45 miles traveled by 2nd cyclist ( as he travels @ 10 mph )
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