Question

A car travels from a place X to place Y at
an average speed of v km/hr, from Y to
X at an average speed of 2v km/hr,
again from X to Y at an average speed of
3v km/hr and again from Y to X at an
average speed of 4v km/hr. Then the
average speed of the car for the entire
journey
(a) is less than v km/hr
(b) lies between v and 2v km/hr
(c) lies between 2v and 3v km/hr
(d) lies between 3v and 4v km/hr​

Answer 1

Answer:

24 km/h

Explanation:

Let distance from A to B be x

Time for travel from A to B= x/20

Time for travel from B to A= x/30

Hence,speed for total distance 2x is:

$\frac{2x}{ \frac{x}{30} + \frac{x}{20} } = \frac{2x \times 60}{5x} = 24km \: {hr}^{ - 1}$