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Grade 8 Probability Quiz

Probability Scale, Outcomes, Relative Frequency and Complements

What this quiz covers

grade8_probability_quiz1 draws its questions at random from a bank of 13 questions, with full worked solutions for every one.

Worked examples

A few of the question types, with full solutions, so you know what to expect.

What is the probability of an impossible event?

  1. 0
  2. 1
  3. \(\dfrac{1}{2}\)
  4. \(-1\)

Answer: 0

\(\text{The probability scale runs from 0 (impossible) to 1 (certain).}\)

How many outcomes are in the sample space of one roll of a fair six-sided die?

  1. 6
  2. 3
  3. 12
  4. 1

Answer: 6

\(\text{Sample space: } \{1;\ 2;\ 3;\ 4;\ 5;\ 6\}\)

A fair die is rolled. What is \(P(\text{even number})\)?

  1. \(\dfrac{1}{2}\)
  2. \(\dfrac{1}{3}\)
  3. \(\dfrac{1}{6}\)
  4. \(\dfrac{2}{3}\)

Answer: \(\dfrac{1}{2}\)

\(\text{Favourable outcomes: } \{2;\ 4;\ 6\} \text{ — 3 of 6}\)

\(P=\dfrac{3}{6}=\dfrac{1}{2}\)

A fair die is rolled. What is \(P(\text{more than } 4)\)?

  1. \(\dfrac{1}{3}\)
  2. \(\dfrac{1}{2}\)
  3. \(\dfrac{2}{3}\)
  4. \(\dfrac{1}{6}\)

Answer: \(\dfrac{1}{3}\)

\(\text{Favourable outcomes: } \{5;\ 6\} \text{ — 2 of 6}\)

\(P=\dfrac{2}{6}=\dfrac{1}{3}\)

A bag holds 4 red, 5 blue and 1 green bead. What is \(P(\text{red})\)?

  1. \(\dfrac{2}{5}\)
  2. \(\dfrac{4}{6}\)
  3. \(\dfrac{1}{4}\)
  4. \(\dfrac{4}{5}\)

Answer: \(\dfrac{2}{5}\)

\(\text{Total beads: } 4+5+1=10\)

\(P(\text{red})=\dfrac{4}{10}=\dfrac{2}{5}\)