Question

a car travels first one upon three of the distance ab kilometre at 24 km per hour next one upon three of the distance at 30 km per hour and last one upon three of the distance at 40 km per hour its average speed in kilometre per hour for the whole journey his​

Answer 1

Answer:

So, let times taken for the first, second and third halves of the journeys be t1, t2, and t3 respectively. Then,

t1 = x/10

t2 = x/20

t3 = x/60

So, average speed = x / (t1 + t2 + t3)

= x / (x/10 + x/20 + x/60)

= 3/ ((6 + 3 + 1)/60)

= (3×60)/10

= 30 km/hr