<PRE><B>Question 562282</B>
Joe speed = 6 mph
Ken speed = x mph

Joe starts 10 minutes early
so he has run 6*10/60 = 1 mile before ken starts

distance Ken has to run to catch up = 6-1=5 miles

catchup time = 20 minutes ( from 7:10 to 7:30)= 2/3 hours

speed = d/t

speed = 5/(2/3)

speed = 5 *3/2

speed = 15/2 = 7.5 mph

CHECK
catchup time = 2/3 
Joe started 1/6 hour early
so he ran for 2/3 +1/6 = 5/6 hours
his speed = 6 mph
5/6 hour *6 = 5 miles



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