Question

Two numbers from S = {1, 2, 3, 4, 5, 6} are selected one by one without replacement. The probability that minimum of the two numbers is less than 4 is ______ 

(a) (1/15)

(b) (14/15)

(c) (1/5)

(d) (4/5)

Answer 1

The correct option (d) (4/5)  

Explanation:

 S = {1, 2, 3, 4, 5, 6}

A = minimum of two numbers < 4

A' = minimum number ≥ 4 i.e. 4, 5, 6.

∴ P(A) = 1 – P(A') = 1 – (3/6)(2/5) = 1 – (1/5) = (4/5).