A car covers (1/3) part of total distance with a speed of 20 km hr-1 and second (1/3) part with a speed of 30 km hr-1 and the last (1/3) part with a speed of 60 km hr-1. The average speed of the car is

Question

A car covers (1/3) part of total distance with a speed of 20 km hr-1 and second (1/3) part with a speed of 30 km hr-1 and the last (1/3) part with a speed of 60 km hr-1. The average speed of the car is (A) 55 kmhr-1 (B) 30 kmhr-1 (C) 45 kmhr-1 (D) 37.3 kmhr-1

Tardigrade Admin · Accepted Answer

t1 = (s/3/20) = (5/60) ; t2 = (s/3/30) = (5/90) t3 = (s/3/60) = (5/180) vav = (s/t1 + t2 + t3) = (s/(s)60 + (s)90 + (s/180) = 30 km/h

Q. A car covers $\frac{1}{3}$ part of total distance with a speed of $20 km h r^{- 1}$ and second $\frac{1}{3}$ part with a speed of $30 km h r^{- 1}$ and the last $\frac{1}{3}$ part with a speed of $60 km h r^{- 1}$ . The average speed of the car is

$55 kmh r^{- 1}$

$30 kmh r^{- 1}$

$45 kmh r^{- 1}$

$37.3 kmh r^{- 1}$

$t_{1} = \frac{s /3}{20} = \frac{5}{60}; t_{2} = \frac{s /3}{30} = \frac{5}{90}$

$t_{3} = \frac{s /3}{60} = \frac{5}{180}$

$v_{a v} = \frac{s}{t _{1} + t _{2} + t _{3}}$

$= \frac{s}{\frac{s}{60} + \frac{s}{90} + \frac{s}{180}} = 30 km / h$

Q. A car covers 31​ part of total distance with a speed of 20kmhr−1 and second 31​ part with a speed of 30kmhr−1 and the last 31​ part with a speed of 60kmhr−1. The average speed of the car is

55kmhr−1

30kmhr−1

45kmhr−1

37.3kmhr−1