Pass Check: Probability & Statistics
Probabilities add to 1; use fractions, decimals or percentages consistently.
Probability
A measure from 0 to 1 of how likely an event is to happen.
Mutually exclusive
Events that cannot both happen at the same time.
Independent events
Events where one happening does not affect the probability of the other.
Relative frequency
An estimate of probability found from experimental results: frequency ÷ total trials.
Quick check
Mixed quiz
1. The probability that it rains on Saturday is 3/8. Independently, the probability that a bus is late is 4/9. Calculate the probability that it rains and the bus is late.
2. A bag has 20 counters, 8 of which are red. One counter is picked at random. Find the probability it is red.
3. The probability of a spinner landing on blue is 3/6. The spinner is spun 72 times. Calculate the expected number of blue results.
4. The probability that it rains on Saturday is 2/6. Independently, the probability that a bus is late is 3/7. Calculate the probability that it rains and the bus is late.
5. The probability that it rains on Saturday is 4/6. Independently, the probability that a bus is late is 1/7. Calculate the probability that it rains and the bus is late.
6. A bag contains 7 red, 8 blue and 4 green counters. One counter is taken at random. State the probability that it is red, as a fraction in its simplest form.
7. The probability that it rains on Saturday is 2/7. Independently, the probability that a bus is late is 3/7. Calculate the probability that it rains and the bus is late.
8. The probability of a spinner landing on blue is 4/8. The spinner is spun 104 times. Calculate the expected number of blue results.