Q1. What is the total number of units in ratio 2:3:5?
✔ Add all parts together to find total units.
Q2. If 10 units equal $12.50, what is 1 unit?
✔ Divide the total amount by the total number of units.
Q3. Mei Ling has 5 units. How much money does she have?
✔ Multiply the number of units by the value of one unit.
Show transcript
[Slide 1] Understanding Three-Part Ratios
Imagine Ravi, Siti, and Wei Ming sharing lunch money at Tampines MRT. We compare their amounts using three parts instead of two. This helps us see the relationship between all friends.
[Slide 2] Using the Bar Model Method
We draw rectangular bars representing each person's share. The length shows the ratio parts clearly. Always add all units to find the total value.
[Slide 3] Solving a PSLE Word Problem
Ravi, Siti, and Mei Ling saved money for a trip to Sentosa. Their savings are in the ratio two to three to five. Together they have twelve dollars and fifty cents.
[Slide 4] Calculating the Value of Units
First, add two plus three plus five to get ten units. Divide twelve dollars fifty cents by ten to find one unit is one dollar twenty-five cents. Mei Ling has five units, so multiply five by one dollar twenty-five cents.
[Slide 5] Avoiding Common Errors
Many students forget to include the third person's units in the total. Always check that your final answers add up to the original amount. This ensures your calculation is accurate.
[Slide 6] Key Takeaways for PSLE
Remember to draw the bar model for all three friends. Find the value of a single unit before calculating shares. Practice this method for your upcoming PSLE exam.