Question

A room has three lightbulbs. each one has a 10% probability of burning out within the month. what is the probability that all three will be lit at the end of the month?

Answer 1

10% chance of burning out
100-10= 90% chance of not burning out
90% = 0.9
3 lightbulbs
0.9^3 = 0.729 = 72.9%
The probability that all 3 lightbulbs stay lit by the end of the month is 72.9%