Q: In an economy pack of 12 highlighters, 3 are defective.
If you purchase 2 highlighters (picked randomly), what is the probability that neither highlighter is defective?
Since there are 3 defective highlighters out of 12, the probability of selecting the first non-defective highlighter is 9/12.
The probability of selecting the second non-defective highlighter is 8/11 as 11 highlighters remain and only 8 of them are good.
Therefore, the probability that a customer buys 2 non-defective highlighters is:
= 9/12 x 8/11
= 3/4 x 8/11