Question

3 cards are given, one of them is red on both sides, one is blue on both sides \& one is blue on one side and red on the other side. One of them is chosen randomly \& put on the table. It shows red colour on the upper side. The chance of the other side of the card being red is :

• A. $ \frac{2}{3}$
• B. $\frac{1}{2}$
• C. $\frac{3}{4}$
• D. $\frac{1}{3}$

Answer 1

Answer: (A)

$ B_1=$ both sides are red;
$B_2=$ both sides are blue
$; B_3=$ one red $\&$ one blue
$P \left( A / B _1\right)=1 ; P \left( A / B _2\right)=0 ; P \left( A / B _3\right)=1 / 2$