NDA 2 2024 Maths, question 105

Topic: Probability

Q105

A die has two faces with number $4$ , three faces with number $5$ and one face with number $6$ . If the die is rolled once, then what is the probability of getting $4$ or $5$ ?

(a) $1/3$
(b) $2/3$
(c) $5/6$ Correct answer
(d) $1/2$

Solution.

Answer: (c) $5/6$

For the usual fair six-faced die, five of its six faces are labelled 4 or 5.
Therefore P(4 or 5)=(2+3)/6=5/6.
This calculation uses equally likely faces, not equally likely distinct printed numbers.