ALL EXPERIMENTS
Ganita Prakash · Grade 8, Part-II · Chapter 3

Proportional Reasoning – 2

From idli batter to map scales to pie charts — ratios describe how quantities relate. Click through the tabs to test proportionality, split a whole in any ratio, build a pie chart by hand, and tell direct proportion apart from its trickier cousin, inverse proportion.

1 Are Two Ratios Proportional?

Two ratios a:b and c:d are proportional exactly when a×d = b×c (cross-multiplication). Try Viswanath's and Puneet's idli batter.

: and :

2 Ratios in Maps — Representative Fraction

A map scale like 1:60,00,000 means 1 cm on the map equals 60,00,000 cm on the ground. Measure a map distance and find the real one.

3 Scaling a Ratio with Many Terms

Viswanath's spice mix is coriander : chillies : toor dal : fenugreek = 8:4:2:1. If you only have some of one ingredient, scale the whole ratio to match.

4 Dividing a Whole in a Given Ratio

Split any total into parts using a ratio with as many terms as you like — like mixing 110 units of concrete as cement : sand : gravel = 1 : 1.5 : 3.

5 Build a Pie Chart from a Ratio

Every slice's angle is proportional to its share of 360°. Enter grade counts (or any category data) and watch the pie chart draw itself.

6 Construct a Triangle from an Angle Ratio

Angles in a triangle always add to 180°. Give a 3-term ratio and see the triangle drawn to scale.

7 Can a Triangle Have These Side Ratios?

Not every ratio works for sidelengths! The triangle inequality says any two sides must together be longer than the third.

8 Direct or Inverse? The Rule of Three

Direct: both quantities rise together (x₁/y₁ = x₂/y₂). Inverse: one rises as the other falls (x₁y₁ = x₂y₂). Pick a type and solve for the missing value.

Try: 20 workers take 4 days (y₁). If only 10 workers (x₂) are available — inverse proportion — how many days?

9 Working Together — Combined Rates

If Ram alone takes t₁ hours and Shyam alone takes t₂ hours for the same job, how long do they take working together?

Check Your Understanding

Test what you've learned across all nine stations.

Score: 0 / 0