Question

The probability of a person winning a game is 0.8, the probability of him losing a game is__.

Answer 1

Given,

P (winning a game) = 0.8

Winning or losing a game are complementary events.

Also, for complementary events, $P\left(A\right)$ + $P\left(\overline{A}\right)$ = 1.

Because the sum of probabilities of an event and its complementary event is always 1.
$\Rightarrow$ P(winning a game) + P(losing a game) = 1
Then, P(losing a game) = 1 - P(winning a game) = 1 - 0.8
$\Rightarrow$ P(losing a game) = 0.2

Therefore, the probability of losing a game is 0.2.