Question

A train travels at a certain average speed for a distance of 63 km and then Travels at a distance of 72 km at an average speed of 6 km per hour more than its original speed if it takes 3 hours to complete total then the journey what is the original average speed​

Answer 1

Answer:

Step-by-step explanation:

distance of 63km and then travels a distance of 72km at an average speed of 6km/hr more than its original speed.

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If it takes 3 hours to complete the total journey,what is its original average speed.

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Original-speed DATA:

distance = 63 km ; rate = x km/hr ; time = 63/x hrs.

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Faster-speed DATA:

distance = 72 km ; rate = (x+6)km/hr ; time = 72/(x+6) hrs.

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Equation:

time + time = 3 hrs

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

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

21(x+6) + 24x = x(x+6)

45x + 21*6 = x^2+6x

x^2-39x-21*6 = 0

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x^2-39x-126 = 0

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

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Positive solution:

x = 42 km/hr (original rate)

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