Question posted by Adwin from Singapore:
Grade/Level: Primary 4
Question solved by Model Method: There were a total of 126 cars and motorcycles in a car park and there were 446 wheels together. How many motorcycles were there in the car park?
Step 1: First, let's assume all the vehicles in the car park are motorcycles. Each motorcycle would have 2 wheels. Draw a box to represent 1 motorcycle with 2 wheels.
Step 2: Draw an arrow to the right to show that this box is repeated 126 times (label "126" at the end of the arrow).
Step 3: Since all the vehicles have only 2 wheels.
126 vehicles X 2 wheels = 252 wheels
Thus, they have a total of 252 wheels (if they were all motorcycles).
Step 4: Since there are 446 wheels in reality, the extra wheels must belong to the cars (cars have 4 wheels instead of 2). So, let's draw another long box to the right to represent the extra wheels.
446 wheels - 252 wheels = 194 wheels
Hence, there are 194 "extra wheels".
Step 5: Since the wheels belong to the cars, each car should get 2 extra wheels each.
194 extra wheels / 2 extra wheels per car = 97 cars
126 vehicles - 97 cars = 29 motorcycles
Therefore, there are 29 motorcycles.