Shree Travels at a distance of 12 km from her house to school by a bus at 20km/hr and returns home at 16km/hr.
1Calculate the time required to reach school from home.
2. Find out the time required to reach home from school.
3. Determine the aver distance of the entire journey
Answers
A boy goes from his house to school by bus at a speed of 20 km h
−1
and returns back through the same route at a speed of 30 km h
−1
. The average speed of his journey is:
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ANSWER
Let the distance between the school and the house is x km
Speed of the boy from house to school =20 km/hr.
Using formula, Time taken =
speed
distance
.
So, time taken =
20
x
hours.
Also,Speed of the boy from school to the house =30 km/hr
So, time taken =
30
x
hours.
Total time taken =
20
x
+
30
x
=
12
x
hours
Also total distance covered by boy =x+x=2x km.
Using formula,
Average speed =
Totaltime
Totaldistance
=
12
x
2x
=24 km/hr.
Thus, average speed of the boy's journey is 24 km/hr.
Answer:
1). Distance between home and school = 12 km
Speed of bus from her house to school = 20 km/hr
Time required to reach the school from the home = Distance travelled/Speed
Time= 12km/20km/hr
Time= 3/5 hr
Time=3/5 x 60 min
Time = 3 x12 min
Time = 36 min
Hence, The time required to reach the school from the home =36 minutes.
2) Distance =12 km
Speed =16 km/hr
Time = Distance travelled /Speed
Time= 12km/16km/hr
Time = 3/4 hr
Time= 3/4x60 min
Time= 3x15 min
Time= 45 min
Hence, The time required to reach the school from the home = 45 minutes.
3)Average distance =Total distance / 2 km
Average distance = (12+12) / 2 = 24/2 = 12 km
Average speed =Total distance travelled /Total time taken
Average speed = (12+12) km / 36 min+45 min
=24 km / 3/5+3/4 hr
=24km / (12+15)/20 hr
=24 km / 27/20 hr
=24 km *27/20 hr
=648 km / 20 hr
=32.4 km/hr.