Question

A vehicle travels 24 km with a constant speed of 65 km/h and another 50 km with a constant speed of 80km. What is the average speed

Answer 1

Answer:

speed=65km/hr

distance=24km

time taken to complete 24 Km=24/65

speed=80km/hr

distance=50km

time taken to complete 50km= 50/80

average speed=total distance travelled/total time taken

average speed=24+50/(24/65+50/80)

=74/(24/65+5/8)

=74/({192+325}/520)

=74*520/517

=74km/hr(approx)

Answer 2

$g$

speed=distance/time............. (1)

average speed = total distance/total time

here, total distance = 24+50=74

from equation (1) time = distance/sped

case :- 1

distance = 24 km

speed = 65 km/h

so, time = distance/ speed

time = 24/65.........(2)

case :- 2

distance = 50 km

speed = 80 km/h

so, time = distance/speed

time = 50/80...... (3)

from, case :- 1 & 2

total time = 24/65 + 50/80

now, average speed = total distance/total time

average = (74)/ (24/65)+(50/80)

= (74×65×80)/ (24×80)+(65×50)

= (384800)/ (1920+3250)

average speed = (384800)/(5170)

average speed = 74.429 km/h