Question

The probability that an event A happens in one trial of an experiment is 0.4. Three independent trial of the experiment are formed. The probability that the event A happens at least once is

• A. 0.934
• B. 0.784
• C. 0.548
• D. 0.343

Answer 1

The correct option is B 0.784

Probability that A happens = 0.4

Probability that A doesn't happen
= 1 - 0.4 = 0.6

So required probability = 1 - Probability (that) does not happens i.e. not even one in three time

$=1-\left(0.6\right)\times \left(0.6\right)\left(0.6\right)$

$=1-0.216$

$=0.784$