8. A train travels at a certain average speed for a distance 63 km and

1.	8. A train travels at a certain average speed for a distance 63 km and then travels adistance of 72 km at an average speed of 6 km/hr more than the original speed. If ittakes 3 hours to complete total journey, what is its original asverage speed?
Answer» Let original speed of the train be x km/h. Time taken to travel 63 km = 63/x hours New speed = (x + 6) km/hr Time taken to travel 72 km = 72/(x + 6) hours According to the question, 63/x +72/(x + 6) = 3 x2- 39x - 126 = 0 (x - 42)(x + 3) = 0 x = -3 or x = 42 As the speed cannot be negative, x = 42 Thus, the average speed of the train is 42 km/hr.

8. A train travels at a certain average speed for a distance 63 km and then travels adistance of 72 km at an average speed of 6 km/hr more than the original speed. If ittakes 3 hours to complete total journey, what is its original asverage speed?

Answer»

Let original speed of the train be x km/h.

Time taken to travel 63 km = 63/x hours

New speed = (x + 6) km/hr

Time taken to travel 72 km = 72/(x + 6) hours

According to the question,

63/x +72/(x + 6) = 3

x2- 39x - 126 = 0

(x - 42)(x + 3) = 0

x = -3 or x = 42

As the speed cannot be negative, x = 42

Thus, the average speed of the train is 42 km/hr.