Question

Question 13 Fill in the blanks in following table:






P(A) P(B) P(A ∩ B) P(A U B)


(i) 1/3 1/5 1/15 …


(ii) 0.35 ... 0.25 0.6


(iii) 0.5 0.35 ... 0.7

Class X1 - Maths -Probability Page 405

Answer 1

(i) P( A ) = 1/3 , P( B ) = 1/5, P( A ∩ B ) = 1/15
we know,
P( A U B ) = P( A ) + P( B ) - P( A ∩ B)
= 1/3 + 1/5 - 1/15
= ( 5 + 3 - 1)/15
= 7/15

(ii) P( A ) = 0.35 , P( A ∩ B) = 0.25 , P(A U B) = 0.6
we know ,
P( A U B ) = P( A ) + P( B ) - P( A ∩ B)
0.6 = 0.35 + P( B ) - 0.25
0.6 = (0.35 - 0.25) + P( B )
0.6 - 0.1 = P( B )
P( B ) = 0.5

(iii) P(A ) = 0.5 , P( B) = 0.5 and P( A U B ) = 0.7
we know,
P( A U B ) = P( A ) + P( B ) - P( A ∩ B)
0.7 = 0.5 + 0.5 - P( A ∩ B )
0.7 = 1 - P( A ∩ B )
P( A ∩ B ) = 0.3