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.

Question

Philoid · Accepted Answer

Given: Math students = 30%

Chemistry Students = 20%

Math & Chemistry both = 10%

To Find: P(Math or Chemistry)

Now, P(Math)

P(Chemistry)

P(Math ∩ Chemistry)

We know that,

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%.