Question

A bus travels a distance of 100 Km with a speed of 50km/h and returns with a speed of 30km/h.calculate the average speed for the entire journey​

Answer 1

Answer:

Given:

Bus travels distance of 100 km with a speed of 50 km/hr and returns with a speed of 30 km/hr

To find:

Average speed for the entire journey

Concept:

Average speed is defined as the ratio of Total distance travelled to the total time taken. Since it involves distance, average speed is always positive.

Calculation:

$avg. \: v = \dfrac{total \: distance}{total \: time}$

$= > avg. \: v = \dfrac{(100 + 100)}{ \dfrac{100}{50} + \dfrac{100}{30} }$

Cancelling 100 on numerator and denominator:

$= > avg. \: v = \dfrac{(2)}{ \dfrac{1}{50} + \dfrac{1}{30} }$

$= > avg. \: v = \dfrac{2 \times( 30 \times 50)}{50 + 30}$

$= > avg. \: v = \dfrac{150}{4}$

$= > avg. \: v = 37.5 \: km {hr}^{ - 1}$

So final answer :

$\boxed{ \red{ \bold{ \huge{avg. \: v = 37.5 \: km {hr}^{ - 1} }}}}$

Answer 2

Answer:

37.52 km / hr

Explanation:

Given :

Distance = 100 km

Speed = 50 km / hr

First case :

We know :

Time = Distance / Speed

Time = 100 / 50 hr

T = 2 hr

Second case :

Distance = 100 k m

Speed = 30 km / hr

Time = 100 / 30 hr

T' = 3.33 hrs.

Now we know :

Average speed = Total distance covered / Total time taken :

A.S. = ( 100 + 100 ) / ( 2 + 3.33 ) km / hr

A.S. = 200 / 5.33 km / hr

A.S. = 37.52 km / hr

Hence we get required answer.