NCERT Class XI Mathematics - Probability - Solutions
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Question : 41
Total: 54
In Class XI of a school 40% of the students study Mathematics and 30% study Biology. 10% of the class study both Mathematics and Biology. If a student is selected at random from the class, find the probability that he will be studying Mathematics or Biology.
Solution:
Let E and F be the events that students study Mathematics and Biology respectively. Probability that students study Mathematics i.e.,
P (E) =
Probability that students study Biology i.e.,
P (F) =
Probability that students study both Mathematics and Biology i.e.,
P (E ∩ F) =
We have to find the probability that a student studies Mathematics or Biology, i.e., P (E ∪ F)
Now, P (E ∪ F) = 0.4 + 0.3 – 0.1 = 0.6
P (E) =
Probability that students study Biology i.e.,
P (F) =
Probability that students study both Mathematics and Biology i.e.,
P (E ∩ F) =
We have to find the probability that a student studies Mathematics or Biology, i.e., P (E ∪ F)
Now, P (E ∪ F) = 0.4 + 0.3 – 0.1 = 0.6
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