Question

a train moves with a speed of 30 km per hour in the first 15 minute with another a speed of 40 km per hour the next 15 minutes and then with a speed of 60 km per hour in last 30 minutes calculate the average speed of the train for his journey .pls answer

Answer 1

speed=s1=30km/hr
time=t1=15min=1/4 hours

distance=di= s1*t1

d1 =30/4= 7.5km

similarly
d2=10km

d3=30km

avg speed=(d1+d2+d3)/(t1+t2+t3)

avg speed=(7.5+10+30)/1

avg speed=47.5km/hr

Answer 2

solution

v1= 30 km/h

t1= 15 minutes= 0.25 hour

so distance covered (d1)= v1×t1= 7-5 lm

v2= 40km/hour

t2= 15 minutes= 0.25 hour

distance covered (d2)= 10 km

v3= 60 km/hour

t3= 30minutes=0.5 hour

distance covered (d3)= 30 km

average speed

= total distance/total time

= (d1+d2+d3) /(t1+t2+t3)

(7.5+10+30) / (0.25+0.25+0.5)

= 47.5/1

= 47.5 km / hour

ANSWER= 47.5 KM/ HOUR