Compare likelihoods, identify dependent events and interpret variation in repeated experiments.
Example 1
A fair coin has landed heads 7 times in a row. Which statement about the next toss is correct?
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Answer: Heads and tails are still equally likely
- Separate tosses of a fair coin are independent.
- Earlier results do not change the two equally likely outcomes of the next toss.
Example 2
Two groups each toss a fair coin 30 times. Group A records 13 heads; group B records 17 heads. How many more heads did the group with the larger count record?
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Answer: 4
- Compare the observed counts, not a promised outcome.
- The difference is 17−13=4. Different trial results can occur by chance.
Example 3
A coin is tossed 30 times. The record shows 12 heads and the remaining results are tails. How many tails occurred?
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Answer: 18
- Every toss has one recorded result, heads or tails.
- 30−12=18 tails.