Question

In a shipment of 50 calculators ,4 are effective. Two are calculators are randomly selected and tested. What is the probability that both are defective if the first one is not replaced after being tested

Answer 1

\[46/50\] is the original probability, so you would have 46 out of 50 chances to get a defective calculator. When selecting the second calculator, if the first one is defective, then the total number of remaining calculators is 49 and the total number of defective calculators is 45. Thus, the probability that the second calculator is defective is \[45/49\]Multiply the two fractions, then simplify to lowest terms. To make it easier, simplify \[46/50\]to \[23/25\]