Ten cards numbered 1 to 10 are placed in a box, mixed up thoroughly and then one card is drawn
randomly. If it is known that the number on the drawn card is more than 3, what is the probability
that it is an even number?  Choose one
A) 3/5 B) 3/7 C) 4/7 D) 4/9 E) 5/3
Let A be the event ‘the number on the card drawn is even’ and B be the   event ‘the number on the card drawn is greater than 3’. We have to find P(A|B).   Now, the sample space of the experiment is S = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}   Then A = {2, 4, 6, 8, 10}, B = {4, 5, 6, 7, 8, 9, 10}   and A n B = {4, 6, 8, 10}   Also P(A) = 5/2, P(B) = 7/10 and P(A n B) = 4/10   Then P(A|B) = P(A n B)/P(B) = (4/10)/(7/10) = 4/7   4/7)
<result>C</result>
Ten cards numbered 1 to 10 are placed in a box, mixed up thoroughly and then one card is drawn
randomly. If it is known that the number on the drawn card is more than 3, what is the probability
that it is an even number?