Question

For a biased die the probabilities for different faces to turn up are given below

Face :	1	2	3	4	5	6
Probability	0.1	0.32	0.21	0.15	0.05	0.17

The die is tossed and you are told that either face 1 or 2 has turned up. Then the probability that it is face 1, is

• A. $\frac { 5 } { 21 }$
• B. $\frac { 5 } { 22 }$
• C. $\frac { 4 } { 21 }$
• D. None of these

Answer 1

Answer: (A)

$\frac { 5 } { 21 }$

Answer 2

Required probability $= \frac { 0.1 } { 0.1 + 0.32 } = \frac { 0.1 } { 0.42 } = \frac { 5 } { 21 }$.