car travels first 80 km with the speed of 70 km/h and next 40 km with the speed of 140 km/h. find its average speed.
Answers
Answered by
1
Answer:
Let the each half of the running time be t.
During first half time, speed of car is 80 km/h
Distance covered d
1
=80t km
During second half time, speed of car is 40 km/h
Distance covered d
2
=40t km
Total distance covered d=d
1
+d
2
=80t+40t=120t
Total time taken T=2t
Average speed v
avg
=
T
d
=
2t
120t
=60 km/hr
Answered by
1
Speed = distance/time
According to the first condition;
70 = 80/t
80/70 = t
8/7 = t
1.14 hours = t --------- 1
According to the second condition;
140 = 40/t
40/140 = t
4/14
0.28 hours = t --------- 2
Now, Average speed;
= Total distance/total time taken
= 80 + 40/1.14 + 0.28
= 120/1.42
= 12000/142
= 84.50 km/h
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