Calculating Probability for Complement of an Event
In a school, ...
Question
In a school, there are 120 students. 20 students have no pets, 46 have only 1 pet, 33 have 2 pets, and 21 have at least 3 pets. If a student is picked at random, what is the probability that the student has at least 1 pet?
A
16
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B
26
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C
46
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D
56
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Solution
The correct option is D56 P(student has at least one pet)=1−P(student has no pets)
P(student has no pets)=20120=16
P(student has at least one pet)=1−16=56
AlternateSolution:–––––––––––––––––––––––
Given:
Total number of students = 120
Number of students with exactly 1 pet = 46
Number of students with exactly 2 pets = 33
Number of students with exactly 3 pets = 21
To find: P(at least 1 pet)
Number of students with at least 1 pet = 46 + 33 + 21 = 100