What this guide covers
Selected Sec 1 N2 skills: ratio in simplest form and part-to-whole reasoning. Map area scales and direct or inverse proportion are later work.
Read the labels before dividing
In a ratio A:B, the first number belongs to A. If the ratio is 3:5, the whole has eight parts; A is 38 of the whole, not 35.
Make the units match
Express 0.75 L : 250 mL in simplest form.
- Convert 0.75 L to 750 mL.
- The ratio is 750:250. Divide both terms by 250 to obtain 3:1.
Check: Both amounts now use mL. The first quantity is three times the second.
Try it yourself
Work on paper, then compare the steps. These checks do not establish mastery.
Simplify 40 cm : 1.2 m.
Convert 1.2 m to 120 cm. Then 40:120 = 1:3. Comparing 40 to 1.2 directly would mix units.
Red and blue counters are in the ratio 3:5. There are 40 counters altogether. How many are red and how many blue?
There are 8 parts, so each part is 40÷8=5 counters. Red =3×5=15; blue =5×5=25. The counts add to 40.
Where this connects
- Sec 1 ratio scope →
See the topic beside other Sec 1 number skills.
- Next: scales and proportion →
Sec 2 extends ratio to map scales and direct or inverse relationships.
Sources and scope
Original Mentora examples and checks. The selected ratio and unit skills follow the Sec 1 N2 scope in the MOE G2/G3 Mathematics syllabus; no school-paper questions or graphics were used.