Question

The probability of happening an event A in one trial is 0.4. The probability that the event A happens at least once in three independent trials is

• A. 0.936
• B. 0.784
• C. 0.904
• D. 0.216

Answer 1

Answer: (B)

0.784

Answer 2

Here $P ( A ) = 0.4$ and $P ( \bar { A } ) = 0.6$

Probability that A does not happen at all $= ( 0.6 ) ^ { 3 }$.

Thus required probability $= 1 - ( 0.6 ) ^ { 3 } = 0.784$.