Relative & Expected Frequency Flashcards

All 5 cards in this deck

What is the formula for relative frequency (an estimate of probability from experimental data)?

$\dfrac{\text{frequency of the event}}{\text{total number of trials}}$

e.g. 15 sixes in 60 throws gives $\frac{15}{60} = 0.25$

How do you work out an expected frequency?

e.g. $P(\text{A}) = 0.4$ and the spinner is spun 200 times

Expected frequency $=$ probability $\times$ number of trials, so $0.4 \times 200 = 80$

What happens to the relative frequency of an outcome as the number of trials increases, for an unbiased experiment?

It gets closer to the theoretical probability.

True or false? A dice that lands on a six 3 times in 10 throws must be biased.

False. With so few trials results vary by chance; you need many more trials before judging bias.

True or false? If you calculate an expected frequency of 50 sixes in 300 rolls, the dice may still land on six a different number of times.

True. Expected frequency is only an estimate of what to expect on average, not a guarantee of the actual result.