Proportionality · TEKS 7.6F, 7.6G, 7.12B
Graphs & random samples
Graphs show parts of a whole. A random sample lets you predict about a whole population.
Key steps
- Circle graph: part = percent × total.
- Part-to-part: compare two categories (difference or ratio).
- Random sample: everyone has an equal chance of being picked, so there is no bias.
- Predict: (sample count ÷ sample size) × population.
Worked example
12 of 50 randomly chosen students walk to school. The school has 800 students. How many walk?
- Rate = 12/50 = 0.24.
- 0.24 × 800 = 192.
- Answer: about 192 students
Watch out: A sample of the soccer team, or of people in one line, is biased. Only a random sample of the whole group works.
Practice
5 questions with new numbers every set. Get 4 of 5 to mark this topic as practiced.