In a meeting, 70% of the members favour and 30% oppose a certain proposal. A member is selected at random and we take X = 0 if he opposed, and X = 1 if he is in favour. Then, E(X) is :
Answer & explanation
Correct answer: option 1
F → favour
$\vec{F}$ = oppose
P(F) = 70% = $\frac{7}{10}$
$P(\bar{F}) = 30% = \frac{3}{10}$
So $E(X) = 0 × \frac{3}{10} + 1 × \frac{7}{10}$
$\frac{7}{10}$