Probability of Selecting Defective Rolls

B

The probability of selecting a defective roll in the first selection is 3/10. The probability of choosing another defective roll is 2/9. So 3/10*2/9 = 6/90 = 1/15.

To calculate the probability of selecting a defective roll followed by another defective roll, we need to consider the number of possible outcomes and the number of favorable outcomes.

In this case, we have 10 rolls of film in a box, and 3 of them are defective. We want to select two rolls, one after the other.

Let's break down the problem step by step:

Step 1: Probability of selecting a defective roll on the first draw Out of the 10 rolls, 3 are defective. Therefore, the probability of selecting a defective roll on the first draw is 3/10.

Step 2: Probability of selecting a defective roll on the second draw After selecting one roll, there are now 9 rolls left in the box, and 2 of them are defective. Therefore, the probability of selecting a defective roll on the second draw is 2/9.

Step 3: Multiply the probabilities To find the probability of both events happening, we multiply the probabilities from Step 1 and Step 2: (3/10) * (2/9) = 6/90 = 1/15

So, the probability of selecting a defective roll followed by another defective roll is 1/15.

Therefore, the correct answer is B. 1/15, or about 0.07.