Probability and relative frequency

• What does probability measure?

  How likely an event is to happen
• How is probability expressed?

  As a fraction, decimal, or percentage
• What is the range of probability values?

  From 0 (impossible) to 1 (certain)
• What is the formula for calculating probability?

  Probability = Total outcomes / Favorable outcomes
• What is the probability of rolling a 3 on a fair die?

  P(rolling 3) = $\frac{1}{6}$
• What is the probability of picking a red ball from a bag with 4 red, 3 blue, and 5 green balls?

  P(red) = $\frac{4}{12} =$$\frac{1}{3}$
• What are the types of probability?

  • Theoretical Probability: Based on expected outcomes
  • Experimental Probability: Based on actual experiments
  • Mutually Exclusive Events: Events that cannot occur simultaneously
• What is relative frequency used for?

  To estimate probability based on experiments
• How is relative frequency calculated?

  Relative Frequency = Trials / Event occurrences
• What is the relative frequency of getting heads if a coin is flipped 50 times and lands on heads 28 times?

  0.56 (or 56%)
• What is the relative frequency of landing on red if a spinner is spun 100 times and lands on red 40 times?

  0.4 (or 40%)
• How does relative frequency approximate probability?

  • More trials lead to closer approximation
  • Repeated experiments yield expected probability