A box contains 3 fuses 2 of which are known to be defective

A box contains 3 fuses, 2 of which are known to be defective. Two fuses are selected at random, without replacement, from the box.

a)What is the probability that the 2 defective fuses are selected?

b) What is the probability that there is at least 1 defective fuse among the 2 fuses selected?

Solution

A box contains 3 fuses, 2 of which are known to be defective. Two fuses are selected at random, without replacement, from the box.

a)The probability that the 2 defective fuses are selected is:

2/3=0.67

b)The probability that there is at least 1 defective fuse among the 2 fuses selected is:

2/3*1/2=0.33