Shortage and Surplus Step-by-Step approach (P3-P5 Question)
Over the years, our trainers have identified such question to be a common question for exams. Shortage and Surplus happens when there are two scenarios in one question. How to solve it through our Matrix Method step-by-step approach? Read on to find out!
Example:
Yenni wants to buy some hair clips. If she buys 9 similar hair clips, she will have $6 left. If she buys 12 similar hair clips, she will need another $9 more. What is the amount of money Yenni have at first?
Step 1: Draw 2 equal models (to illustrate the total amount of money Yenni has is unchanged )
Step 2: Record 1st set of data for the first model (Look for keywords like “need”, “left”, “leftover”)
1st key information: if she buys 9 hair clips, have $6 left. (“left” means Yenni has the amount of money with her)
Step 3: Record the second set of data for the 2nd model. (Look for keywords like “need”, “left”, “leftover”)
2nd key information: If she buys 12 similar hair clips, she will need another $9 more. (“need” means Yenni do not have the amount of money, hence dotted lines to indicate Yenni need extra, not from the original amount she had)
Step 4: Compare the two models and the difference in objects and cost.
Hence,
3 hair clips-> $6 + $9
= $15
1 hair clip -> $15 ÷ 3
= $5
Amount of money Yenni have at first = model’s solid box
Using 1st model to solve,
9 hair clips -> $5 × 9
= $45
Amount of money Yenni have at first -> $45 + 6
= $51
Using 2nd model to solve,
12 hair clips-> $5 × 12
= $60
Amount of money Yenni have at first-> $60 − 9
= $51
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