Question

Two numbers are selcted at random form the fist six positive intefgers let x denote the larger of the two numbers ontained

Answer 1

The first six positive integers are 1, 2, 3, 4, 5, 6.

We can select the two positive numbers in 6 × 5 = 30 different ways.

Out of this, 2 numbers are selected at random and let X denote the larger of the two numbers.

Since X is the large of the two numbers, X can assume the value of 2, 3, 4, 5 or 6.

P (X =2) = P (larger number is 2) = {(1,2) and (2,1)} = 230

P (X = 3) = P (larger number is 3) = {(1,3), (3,1), (2,3), (3,2)} = 430

P (X = 4) = P (larger number is 4) = {(1,4), (4,1), (2,4), (4,2), (3,4), (4,3)} = 630

P (X = 5) = P (larger number is 5) = {(1,5), (51,), (2,5), (5,2), (3,5), (5,3), (4,5), (5.4)} = 830

P (X = 6) = P (larger number is 6) = {(1,6), (6,1), (2,6), (6,2), (3,6), (6,3), (4,6), (6,4), (5,6), (6,5)} = 1030

Given the above probability distribution, the expected value or the mean can be calculated as follows:

Mean = ∑(Xi×P(Xi)) = 2×230+3×430+4×630+5×830+6×1030=4+12+24+40+6030=14030=143