Question posted by Mike from Singapore:

Grade/Level: 4th Grade

Question solved by Model Method: 1/3 of the mass of Mr Raj is equal to 3/4 of the mass of Teddy. Their total mass is 80kg. Find Teddy's mass. (Use comparison model with fractions)

Answer:

Step 1: This question involves the Equal Concept. First, we draw 3 boxes to represent the total mass(3/3) of Mr Raj.

Step 2: Next, draw 3 boxes below the model of Mr Raj to represent the part of Teddy's mass that is equal to 1/3 of Mr Raj, i.e., 3/4 of Teddy.

Step 3: Since the first 3 boxes of Teddy's model drawn represents 3/4 of Teddy's mass, we will need to draw another 1 box to its right to represent the remaining 1/4 of Teddy's mass.

Step 4: Then, we draw a bracket to the right of the models to denote the total mass of both of them which is 80 kg.

Step 5: We then divide all the unknown units into equal parts to facilitate our calculations.

From the model,

13 units ---------> 80kg

1 unit ---------> 80kg / 13 = 6 2/13kg

4 units ---------> 4 x 6 2/13kg = 24 8/13kg

Therefore, Teddy's mass is 24 8/13kg.

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