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 :

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)  (2/3) (B) (1/2) (C) (3/4) (D) (1/3)

Tardigrade Admin · Accepted Answer

B1= both sides are red; B2= both sides are blue ; B3= one red one blue P ( A / B 1)=1 ; P ( A / B 2)=0 ; P ( A / B 3)=1 / 2

Q. 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 :

$\frac{2}{3}$

$\frac{1}{2}$

$\frac{3}{4}$

$\frac{1}{3}$

$B_{1} =$ both sides are red;
$B_{2} =$ both sides are blue
$; B_{3} =$ one red $&$ one blue
$P (A / B_{1}) = 1; P (A / B_{2}) = 0; P (A / B_{3}) = 1/2$