There are 10 rolls of film in a box and 3 are defective. Two rolls are to be selected one after the other. What is the probability of selecting a defective roll followed by another defective roll?
A) 1/2 or 0.50
B) 1/4 or 0.25
C) 1/120, or about 0.0083
D) 1/15, or about 0.07
E) None of the choices are correct

Question

Quizplus · Accepted Answer

The probability of selecting the first defective roll is 3/10. After removing one defective roll, the probability of selecting another defective roll is 2/9. Therefore, the combined probability is (3/10) * (2/9) = 1/15.

There Are 10 Rolls of Film in a Box and 3