Suppose 10000 tickets are sold in a lottery each for Rs.1. First prize is of Rs.3000 and the second prize is of Rs.2000. There are three third prizes of Rs.500 each. If you buy one ticket, then what is your expectation?

Let X is the random variable for the prize.

Since, $E(X) = \Sigma XP(X)$

$\therefore$ $E(X) = 0 \times \frac{{9995}}{{10000}} + \frac{{1500}}{{10000}} + \frac{{2000}}{{10000}} + \frac{{3000}}{{10000}}$

$= \frac{{1500 + 2000 + 3000}}{{10000}}$

$= \frac{{6500}}{{10000}} = \frac{{13}}{{20}} = {\rm{Rs}}.0.65$