Problema Solution
The rate at which Dan drives his car is 1 1/2 times the rate at which rob drives his truck. Dan leaves the gas station of the interstate 40 minutes after rob leaves the same station and, with both driving non-stop, overtakes rob in 100 miles. Find the rate of rob's truck in miles per hour
Answer provided by our tutors
let 'r' represent the rate Rob drives his truck, then '1.5r' represents the rate Dan drives his car
let 't' represent the time in hours that Rob drove, then 't-40/60' represents the time that Dan drove
distance = speed * time
they both drove the same distance, so we set their speed*time expressions equal to each other:
rt = 1.5r(t-40/60)
solving for 't' we have t=2
so Rob drove for 2 hours and covered 100 miles:
100/2 = 50
Rob's truck drove at 50 mph