A freight train departed from point A to point B in 3 hours, followed by a passenger train whose speed

| May 25, 2021 | education

A freight train departed from point A to point B in 3 hours, followed by a passenger train whose speed is 30 km / h more than the speed of the freight train, 15 hours after it overtook the freight train, which was then at a distance of 300 km from it, Find the speed of the freight train trains.

Based on the problem, we find the time that the first train traveled. To do this, it is necessary to add to the time that the second train was traveling (15 hours), add the time at which it left before the second (3 hours).

1) 15 + 3 = 18 (hours) – the time the first train traveled.

Let us take the speed of the first train as X, then the speed of the second will be equal to (X + 30). From the condition, we know – in 15 hours the second train overtook the first by 300 km. Then using the formula for the path (S (Distance) = V (Speed) * T (time)) we compose the equation:

2) 18 * X – distance traveled by the first train.

15 * (X + 30) – distance traveled by the second train.

18 * X + 300 = 15 * (30 + X),

18 * X + 300 = 450 +15 * X,

18 * X – 15 * X = 450 – 300,

3 * X = 150,

X = 50 (Km / h) – the speed of the first (freight) train.

Answer: 50 Km / h is the speed of a freight train.



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