CUET Preparation Today
A person walks from his house to his office at a speed of $x_1$ km/hr and returns by the same route at a speed of $x_2$ km/hr. What is his average speed? |
$\frac{x_1+x_2}{2}$ $\frac{x_1+x_2}{2x_1x_2}$ $\frac{2x_1x_2}{x_1+x_2}$ $\frac{x_1+x_2}{x_1x_2}$ |
$\frac{2x_1x_2}{x_1+x_2}$ |
Let the distance from office to home =y km.
Then, the time taken for the round trip =y/x1 + y/x2 =y(x1+x2)/x1*x2
Total distance travelled in that round trip = 2y km
Thus, Average speed=2y/[y(x1+x2)]/x1x2 = 2y*x1*x2/[y(x1+x2)]
The correct answer is Option (3) → $\frac{2x_1x_2}{x_1+x_2}$ |
