Question

A car travels 30 km at the uniform speed of 40 km/h and the next 30 km at a uniform speed of 20 km/h. find its average speed.

Answer 1

Answer:

The average speed of the car is 26.66 km/hrs.

Explanation:

Given:

A car travels $30 km$ at a uniform speed of $40 km/h$ and the next $30 km$ at a uniform speed of $20 km/h$.

To find average speed.

We know that,

Speed = Distance / time

then Time = Distance / Speed

Let's the first case be,

s = distance

$s = 30 km$

v = speed

$v = 40 km/hr$

t = time = 30 / 40

$t=3/4 hrs$

then the second case is,

$s = 30 km$

$v = 20 km/hr$

$t = 30 / 20$

$t = 3/2 hrs$

Average Speed = Total distance/ Total time

Simplifying the above equation

Average Speed $=(30 + 30) / (3/4) + (3/2)$

$=60 / ( 3 + 6 ) /4$

$=60 / 9 * 4$

$=20 / 3 * 4$

$=80 / 3$

$=26.66$

Hence,

The average speed of the car exists 26.66 km/hrs.

#SPJ2

Answer 2

Answer:

The answer is 26.66 KM/H

Explanation:

To find

Speed= distance travelled

--------------------------

time taken

Distance=30km

Speed=40km

Time=30/40

=3/4

3/4km/h

Distance= 30 km

Speed=20km

To find

Time= 30/20

3/2km/h

Average speed =total distance travelled/ time taken

=30+30/3×1+3×2

4×1+2×2

60

-----

(3+6)4

9×4

60×4/9

80/3

26.66Km/h

Hence proved