The schoolboy traveled 1/3 of the way on a bus at a speed of 40 km / h, another 1/3 of the way

| August 3, 2021 | education

The schoolboy traveled 1/3 of the way on a bus at a speed of 40 km / h, another 1/3 of the way on a bicycle at a speed of 20 km / h, and covered the last third of the way at a speed of 10 km / h. Determine the average speed of movement of the student.

1. Vav = S / t.
The path and the time are made up of three parts.
2. Let’s denote 1/3 of the path as x. The time that the student rode the bus:
t1 = x / 40.
3. Cycling time:
t2 = x / 20.
4. Walking time:
t3 = x / 10.
5. Total time:
t = t1 + t2 + t3 = x / 40 + x / 20 + x / 10 = x / 40 + 2x / 40 + 4x / 40 = 7x / 40.
6. The total path is equal to:
S = 3x.
7. Find out the average speed.
Vav = 3x / (7x / 40) = 40 * 3x / 7x = 120/7 = 17.14 km / h.
Answer: The average speed of a student is 17.14 km / h.



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