In a class of 23 students, 8 have a cat and 13 have a dog. There are 8 students who do not have a cat or a dog. What is the probability that a student chosen randomly from the class has a dog?
Question
In a class of 23 students, 8 have a cat and 13 have a dog. There are 8 students who do not have a cat or a dog. What is the probability that a student chosen randomly from the class has a dog?
Solution
To solve this problem, we need to determine the number of students who have a dog and then find the probability that a randomly chosen student has a dog.
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Identify the total number of students:
- Total students = 23
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Identify the number of students who do not have a cat or a dog:
- Students without a cat or a dog = 8
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Calculate the number of students who have either a cat or a dog or both:
- Students with a cat or a dog or both = Total students - Students without a cat or a dog
- Students with a cat or a dog or both = 23 - 8 = 15
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Identify the number of students who have a cat:
- Students with a cat = 8
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Identify the number of students who have a dog:
- Students with a dog = 13
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Use the principle of inclusion-exclusion to find the number of students who have both a cat and a dog:
- Students with both a cat and a dog = (Students with a cat) + (Students with a dog) - (Students with a cat or a dog or both)
- Students with both a cat and a dog = 8 + 13 - 15 = 6
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Calculate the number of students who have only a dog:
- Students with only a dog = Students with a dog - Students with both a cat and a dog
- Students with only a dog = 13 - 6 = 7
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Calculate the total number of students who have a dog (either only a dog or both a dog and a cat):
- Total students with a dog = Students with only a dog + Students with both a cat and a dog
- Total students with a dog = 7 + 6 = 13
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Calculate the probability that a randomly chosen student has a dog:
- Probability = (Number of students with a dog) / (Total number of students)
- Probability = 13 / 23
Therefore, the probability that a student chosen randomly from the class has a dog is .
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