Primary 4 Mathematics: Modeling topic (3x questions)

 

There are some good modeling questions from 2018 SA1 test papers as shown below.

Red Swastika School 2018 SA1 Mathematics, question 48.

Question 48: Jason had three times as many red marbles as blue marbles. During a game, he lost 38 red marbles and won another 44 blue marbles. He then had the same number of red and blue marbles. How many red marbles did he have after the game?

You need to know the addition of 44 and 38 actually formed the 2 units.

This is a critical step.

 

Henry Park School 2018 SA1 Mathematics, question 43.

Question 43: Felicia and Yvonne have the same number of sweets at first. After Felicia gave away 17 sweets and Yvonne gave away 35 sweets, Felicia had seven times as many as Yvonne. Find the total number of sweets they had at first.

 

There is no way you can immediately draw the model above at first trial.

After you know Felicia had seven times as many sweets as Yvonne, you then realize you need to draw a long model to clearly indicate each individual unit (total 7 units at Felicia side). While you try to calculate per unit value, 35-17 is actually equal to 6 units.

 

Raffles Girls’ Primary School 2018 SA1 Mathematics, question 44.

Question 44: Mr. Tan had 186 mangoes, grapefruits and apples. There were 8 fewer mangoes than grapefruits. The number of apples was 2 times the total number of mangoes and grapefruits. Mr. Tan packed all the apples into bags of 4 and sold each bag for S$5. How much money did he collect from the sale of all the apples?

This question has a lengthy procedure to reach the final answer.

You need to find the quantities of the apple first. There are couple of ways to draw the model but this is just one straightforward way.

Minus off the 3 x 8 , you are able to find per unit value. From there, you can calculate the quantities of the apple and the final cost.

These are pretty good questions for modeling practices.