Primary 4 Mathematics: Modeling topic (2x questions). The toughest!

By far, these 2 modeling questions are the difficult one I have seen in the SA1 test papers from all the 12 good schools. These 2 questions are from Rosyth School, year 2018 SA1 Mathematics Primary 4, Section C, question 41 and question 43.

 

Question 41: Annie and Sarah had the same number of stickers at first. After Annie had bought 38 stickers and Sarah had lost 25 stickers, Annie had 4 times as many stickers as Sarah. How many stickers did each girl have at first?

 

 

This question tests the students if they understand after the addition of 38 stickers and subtraction of 25 stickers, these 2 figures (38 + 25) are actually 3 units because Annie had 4 times as many stickers as Sarah. Once you get this critical information right, the rest is peanut ! Good question nevertheless.

 

 

Question 43: Belinda had thrice as many sweets as Wanli at first. After Wanli had given away 8 sweets, Belinda had 5 times as many sweets as Wanli. How many sweets did Belinda have?

 

 

This question is tricky. It is not so straightforward to form the final modeling. Firstly, you must know once Wanli had given away 8 sweets, the remaining is a "one unit". You then immediately assign the portion "8" equally at Belinda side. That is an important step.

 

Belinda now had 5 times as many sweets as Wanli. After setting aside the "one unit" (just like Wanli), the remaining forms 4 units. You shall also indicate 1 unit at other 2 blocks at Belinda as they are the same size before (Belinda had thrice as many sweets as Wanli at first). So, minus off that 2 units from your remaining 4 units, you get 2 units = 8x3 = 24. The rest is history.

 

This is by far the toughest modeling question I have seen at P4 mathematics test paper.