6. A journalist drove his car with speed 60 km/hr to travel from Kolkata to
Balasore to cover the cyclone Josh. But he failed to reach the spot and
anticipating the danger ahead he immediately rushed back to Kolkata driving
his car with speed 90 km/hr.
Find the average speed of the whole journey.
...2
Answers
Answer:
: Let Kolkata be a and Balasore be b.
Let the distance between a and b be ‘S’.
Therefore, total distance travelled = S+S=2S
From a to b Speed = distance/time
Therefore, 60 = S/T1, Therefore T1 = S/60
From b to a Speed = distance/ time
Therefore, 90 = S/T2, Therefore T2 = S/90
Average speed = Total distance covered/Total Time Taken => 2S/(T1+ T2)= = 2S/(S/60+S/90) = S/(3S/180+2S/180) = (2Sx180)/3S+2S = (2SX180)/5S = 2x36 = 72
Therefore, Average Speed = 72km/hr
Explanation:
Answer:
: Let Kolkata be a and Balasore be b.
Let the distance between a and b be ‘S’.
Therefore, total distance travelled = S+S=2S
From a to b Speed = distance/time
Therefore, 60 = S/T1, Therefore T1 = S/60
From b to a Speed = distance/ time
Therefore, 90 = S/T2, Therefore T2 = S/90
Average speed = Total distance covered/Total Time Taken => 2S/(T1+ T2)= = 2S/(S/60+S/90) = S/(3S/180+2S/180) = (2Sx180)/3S+2S = (2SX180)/5S = 2x36 = 72
Therefore, Average Speed = 72km/hr