A train travels at the rate of 10 miles/hr for the first hour of a trip, at 20 miles/hr for the second hour, at 30 miles/hr for the third hour and so on. How many hours will it take the train to complete a 550-mile journey? Assume that the train makes no intermediate stops. Choices
A) 8
B) 8.5
C) 9
D) 9.5
E) 10
A train travels at the rate of 10 miles/hr for the first hour of a trip, at 20 miles/hr for the second hour, at 30 miles/hr for the third hour and so on. How many hours will it take the train to complete a 550-mile journey? Assume that the train makes no intermediate stops.   I think the easiest way to solve this problem would be simply to count the number of miles it travels per hour (and in total)   Hour miles/hour Total miles   1 10 10   2 20 30   3 30 60   4 40 100   5 50 150   6 60 210   7 70 280   8 80 360   9 90 450   10 100 550   It takes a total of nine hours to cover the 550 mile distance.   ANSW10R: 10
<result>E</result>
A train travels at the rate of 10 miles/hr for the first hour of a trip, at 20 miles/hr for the second hour, at 30 miles/hr for the third hour and so on. How many hours will it take the train to complete a 550-mile journey? Assume that the train makes no intermediate stops.