Question

The computer repairman is The computer repairman is given 5 computers to test. He knows that out of the 5 computers, there are 3 bad video cards. In addition, out of the 5 computers there are 4 failed hard drives. What is the probability that the first computer he tries has both abad video card and a failed hard drive?

Answer 1

Total computers = 5

Number of computers with bad video cards = 3

Number of computers with failed hard drives = 4

We know the probability of an event is the likelihood of that event occuring. We find this by dividing the number of outcomes of that event by the total number of outcomes.

We want the probability of bad video card AND failed hard drive.

We can write this as:

P(bad vc) AND P(failed hd)

Recall that in probability, AND means multiplication and OR means addition. We can find the probabilty by:

`P(\text{BadVideoCard and FailedHardDrive)=P(bad vc) x P(failed hd)}`

• The probability of bad video card is 3 out of 5

,

• The probability of failed hard drive is 4 out of 5

Thus, our answer will be:

`(3)/(5)*(4)/(5)=(12)/(25)`