Question

A person walks first at a constant speed of 5.50 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 3.50 m/s.
What is her average speed over the entire trip?

Answer 1

Answer:

4.50m/s

Explanation:

speed1=5.5

speed2=3.5

average=1/2(5.5+3.5)=4.5

Answer 2

Answer:

4.27 m/s

Explanation:

Let the distance between A and B be 'x' m.

Speed (from A to B) = 5.50m/s

Time (from A to B) = Distance / Speed

= x/5.50 m

Speed (from B to A) = 3.50m/s

Time (from B to A) = Distance/ Speed

= x/3.50 m

Average speed = Total distance/ Total time

$\frac{x + x}{ \frac{x}{5.50} + \frac{x}{3.50} } \\ \frac{2x}{ \frac{7x + 11x}{38.5} } \\ \frac{2x}{ \frac{18x}{38.5} } \\ 2x \times \frac{38.5}{18x}$

=4.27m/s