To analyze the situation with Sara and her 12 greeting cards, we know there are 3 different designs with each design having an equal number of cards. Each design is a butterfly, shell, or flower. Therefore, each design has:
\[ \frac{12 \text{ cards}}{3 \text{ designs}} = 4 \text{ cards per design} \]
Now, let's evaluate the statements one by one:
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The data does not represent a uniform probability model.
- This statement is incorrect. The cards are evenly distributed among the three designs, so it does represent a uniform probability model.
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Each design has the same probability of being randomly selected.
- This statement is correct. Each design has an equal probability since there are 4 cards of each type in a total of 12 cards.
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The probability of selecting a shell is \( \frac{1}{2} \).
- This statement is incorrect. The probability of selecting a shell card is \( \frac{4}{12} = \frac{1}{3} \).
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The probability of selecting a butterfly or shell design is \( \frac{1}{3} \).
- This statement is incorrect. The probability of selecting a butterfly or shell design is:
- Probability of selecting a butterfly + Probability of selecting a shell = \( \frac{1}{3} + \frac{1}{3} = \frac{2}{3} \).
- This statement is incorrect. The probability of selecting a butterfly or shell design is:
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The probability of selecting a butterfly design is \( \frac{1}{3} \).
- This statement is correct. There are 4 butterfly cards out of 12 total cards, so the probability is \( \frac{4}{12} = \frac{1}{3} \).
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The probability of not selecting a flower design is \( \frac{2}{3} \).
- This statement is correct. The probability of selecting a flower design is \( \frac{1}{3} \), so the probability of not selecting a flower design is:
- 1 - Probability of selecting a flower = \( 1 - \frac{1}{3} = \frac{2}{3} \).
- This statement is correct. The probability of selecting a flower design is \( \frac{1}{3} \), so the probability of not selecting a flower design is:
In summary, the three correct statements are:
- Each design has the same probability of being randomly selected.
- The probability of selecting a butterfly design is \( \frac{1}{3} \).
- The probability of not selecting a flower design is \( \frac{2}{3} \).