Question

In class 11th of a school, 40% of students study mathematics and 30% study biology, 10%of class study both mathematics and biology. If a student is selected at random from class, find the probability that he will be studying mathematics or biology

Answer 1

40/100 =. 4
30/100=. 3
10/100=. 1

We can solve it below
0.4+.0.3-0.1 = 0.6

Answer 2

Answer:

Given: 40% students study Mathematics.

Probability of students studying Mathematics

= 40/100 = 0.4

P(M) = 0.4

 

Given: 30% students study Biology.

Probability of students studying Biology

= 30/100 = 0.30

P(B) = 0.3

P(B) = 0.3 

Given: 10% of students study both mathematics and biology.

Probability of students studying both mathematics and biology

= 10/100 = 0.1

P(M ∩ B) = 0.1

 

Now, we know that:

P(X U Y ) = P( X ) + P( Y ) - P( X ∩ Y )

.°. P( M U B ) = P( M ) + P( B ) - P( M ∩ B)

P( M U B ) = 0.4 + 0.3 - 0.1  

P( M U B ) = 0.6

So, Probability of students study Mathematics or biology is 0.6.