Relative Frequency

Relative frequency

• You need to be able to calculate probabilities for data given in graphs and tables
• You can use this formula to estimate a probability from a frequency table
  • Probability = frequency of outcome / total frequency
• When a probability is calculated like this it is sometimes called a relative frequency

Golden rule

• Probability estimates based on relative frequency are more accurate for larger samples, or for a larger number of trails in an experiment

Examiners report

• In the sample there were 15+10 = 25 eggs that weighed 55g or more, out of a total of 40 eggs
• Don’t round any values here- your answer is an estimate because it is based on a sample

Experimental probability

• You can carry out an experiment to estimate the probability of something happening
• To estimate the probability that the drawing pin will land point up, you calculate the relative frequency
• The most accurate estimate will be based on the largest number of trials