Question

Anju's journey comprises three segments. He travels the first 'd - 30' km at a speed of 12 km/h, the next 'd' km at a speed of 30 km/h, and finally, she covers the remaining 'd + 30' km at a speed of 24 km/h. The question requires determining the value of 'd' given that her average speed for the entire journey is 20 km/h.

A 220 Correct Answer Incorrect Answer
B 150 Correct Answer Incorrect Answer
C 180 Correct Answer Incorrect Answer
D 120 Correct Answer Incorrect Answer
E none of these Correct Answer Incorrect Answer

Solution

ATQ, (d – 30 + d + d + 30)/{(d – 30)/12 + (d/30) + (d + 30)/24} = 20 Or, 3d/{(19d – 150)/120} = 20 Or, 18d = 19d – 150 Or, d = 150

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