A band leader randomly selects 2 students out of 80 band members. If you and your brother are both band members. What is the probability that you are both selected?
A: 1/3160 B: 1/20 C: 1/6320 D: 1/1600

Respuesta :

AL2006

The probability of choosing one of us is      2 / 80 .

If that happens, then the probability of choosing
the other one is  1 / 79 .

The probability of both things happening is

        (2/80) x (1/79) =  1/3160  =  0.0003165... = 0.032... percent