In order to go from a house to school, Hanako walks from the house to the bus stop first.
She takes a bus from there and walks again after she gets off the bus.
For a while after Hanako left the house, her mother noticed s thing left behind and ran after the same way by car.
Then both of them have arrived at school at the same time.
Below is the graph which showed time and distance between Hanako and her mother after Hanako left the house.
Speed Hanako walks and speed of the bus and the car are fixed respectively.
She did not wait for a bus at a bus stop.
Answer the following questions.
(1) Find the speed per minute Hanako walks and the speed per minute of the bus respectively.
(2) Find the distance from the house to the school.
(3) Find the speed per hour of the car.
Answer
(1) 70 m/m, 560 m/m
(2) 7980 m
(3) 39.9 km/h
Solution
(1) 490/7=70 m/m (2730 - 490) / (11 - 7) = 560 m/m
She takes a bus from there and walks again after she gets off the bus.
For a while after Hanako left the house, her mother noticed s thing left behind and ran after the same way by car.
Then both of them have arrived at school at the same time.
Below is the graph which showed time and distance between Hanako and her mother after Hanako left the house.
Speed Hanako walks and speed of the bus and the car are fixed respectively.
She did not wait for a bus at a bus stop.
Answer the following questions.
(1) Find the speed per minute Hanako walks and the speed per minute of the bus respectively.
(2) Find the distance from the house to the school.
(3) Find the speed per hour of the car.
Answer
(1) 70 m/m, 560 m/m
(2) 7980 m
(3) 39.9 km/h
Solution
(1) 490/7=70 m/m (2730 - 490) / (11 - 7) = 560 m/m
(2) 490 + 560 × (20 - 7) + 70 × (23 - 20) = 490 + 7280 + 210 = 7980 m.
(3) The speed per minute of the car is assumed X m/m.
As (X - 560) × (20 - 11) + (X - 70) × (23 - 20) = 2730, X × 12 = 2730 + 5040 + 210 = 7980.
Therefore X = 7980/12 = 665 m/m.
The speed per hour is 665 × 60/1000 = 39.9 km/h.
As (X - 560) × (20 - 11) + (X - 70) × (23 - 20) = 2730, X × 12 = 2730 + 5040 + 210 = 7980.
Therefore X = 7980/12 = 665 m/m.
The speed per hour is 665 × 60/1000 = 39.9 km/h.
