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Home » In class, 30% of the students offered mathematics 20% offered chemistry and 10% offered both. If a student is selected at random, find the probability that he has offered mathematics or chemistry.
In class, 30% of the students offered mathematics 20% offered chemistry and 10% offered both. If a student is selected at random, find the probability that he has offered mathematics or chemistry.
CBSE | Class 11 | Exercise 31B | Maths | Probability Distribution | RS Aggarwal
In class, 30% of the students offered mathematics 20% offered chemistry and 10% offered both. If a student is selected at random, find the probability that he has offered mathematics or chemistry.

Answer : Given: Math students = 30% Chemistry Students = 20%

Math & Chemistry both = 10%

To Find: P(Math or Chemistry)

Now, P(Math) = 30/100= 0.30

P(Chemistry) = 20/100 = 0.20

P(Math ∩ Chemistry) We know that, = 0.10

P(A ???? B) = P(A) + P(B) – P(A ∩ B)

Therefore,

P(Math ???? Chemistry) = 0.30 + 0.20 – 0.10 = 0.40

Hence, number of students studying math or chemistry are 40%.

 

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