SOLUTION: when a truck at a 60 miles per hour, it uses 30% more then it does when it travels at 50 miles per hour. the truck can travel 20 miles on a gallon of gas if it is travelling at 5

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: when a truck at a 60 miles per hour, it uses 30% more then it does when it travels at 50 miles per hour. the truck can travel 20 miles on a gallon of gas if it is travelling at 5      Log On


   

Question 133086: when a truck at a 60 miles per hour, it uses 30% more then it does when it travels at 50 miles per hour. the truck can travel 20 miles on a gallon of gas if it is travelling at 50 miles per hour the truck has only 10 gallon of gas and is of 160 miles from its destination . It takes 20 minutes for the truck to stop for gas how long will it take the truck to reach its final destination if the truck is driven at 60 miles per hour?
Answer by solver91311(24713) About Me  (Show Source):
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20 miles per gallon is the same as 1%2F20 gallon per mile. So the truck uses 1/20 of a gallon of gas per mile driven at 50 miles per hour. At 60 miles per hour, the truck uses 30% more gas, or 1.3%2F20 gallons per mile. 1.3%2F20=.065, so for a 160 mile trip at 60 miles per hour, the truck would use .065%2A160=10.4 gallons of gas. Since the truck has a 10 gallon tank, it would have to stop for gas once during the trip.

Without stopping, the trip would take t=d%2Fr=160%2F60=8%2F3 hours. But since it had to stop once for 20 minutes, or 1/3 hour, the entire trip would take 8%2F3%2B1%2F3=9%2F3=3 hours.