You have backed up your computer on two separate hard drives. The typical failure rate of hard drive failure is 3% per year.

You are given that event A is that your first hard drive fails and event B is that your second hard drive fails.

You wish to find the probability that both hard drives fail in the same year.

Which formula would you use?

P(A) + P(B) - P(A and B)

P(A) * P(B)

1-P(A)

Desireable outcomes/Total outcomes