Question

A bus has to travel a total of 2000 km .... 1/3 of distance it travel at the speed of 50 km / hr. ... the next 1/3 in 30 km / hr.........what should be its speed in the next 1/3 distance so that the total speed comes to be 50 km /hr

Answer 1

use above formula for avg speed of same distance covered by diff velocity

Answer 2

Time taken to complete
1st one-third distance = 2000 / (3 × 50) = 40/3 hours
2nd one-third distance = 2000 / (3 × 30) = 200/9 hours
3rd one-third distance = 2000 / (3v) hours

Average speed = Total distance / Total time
50 = 2000 / (40/3 + 200/9 + 2000/(3v))
40/3 + 200/9 + 2000/(3v) = 400
2000/(3v) = 400 - (40/3 + 200/9)
v = 2000/3 × [1/(400 - (40/3 + 200/9)]
v = 1.829 kmph

Speed of bus should be 1.829 kmph