Part A — Spinners & Probability
Part A — Spinners & Probability
The probability of an event is the fraction of outcomes that are favourable. For a spinner, compare the size of the coloured region to the whole circle.
1
Write the probability of landing on red for each spinner, as a fraction.
A: B: C:
2
Order the three spinners from the least to the greatest chance of red.
3
On spinner C (four equal colours), what is the probability of landing on red or blue?
Answer:
4
On spinner B, what is the probability of not landing on red? Explain how this links to your answer for spinner B in question 1.
5
If you spin spinner A 100 times, about how many reds would you expect? Why is the real result unlikely to be exactly that?
6
Design it. Draw and shade a spinner where the probability of red is exactly 1/3.
Part B — The Probability Scale
Every probability sits between 0 (impossible) and 1 (certain). An even chance sits at ½. The probabilities of an event happening and not happening always add to 1.
1
On the scale above, write the words impossible, even chance and certain in the correct places (0, ½ and 1).
2
Mark each event on the probability scale with its letter.
- R: rolling a 7 on an ordinary 6-sided die
- H: a fair coin landing on heads
- S: the sun rising tomorrow
- E: rolling an even number on a die
- L: rolling a number less than 6 on a die
3
The probability of an event is ¼. What is the probability that it does not happen?
Answer:
4
A bag holds 3 red marbles and 1 blue marble. Write P(red) and P(blue).
P(red) = P(blue) =
5
Theory vs experiment. Jin tosses a fair coin 10 times and gets 7 heads. Does this mean the coin is unfair? Explain.
6
Open challenge. Describe a real event whose probability is close to, but not exactly, 1 (very likely but not certain).