Probability question

Question

Five people are on a team. Two of them are selected at random to attend a competition.

 

How many different groups of two can be selected?

 

and if Mary is one of the five people in the team, what is the probability that she is selected to attend the competition?

 

my thought was she has a 1/5 chance of being chosen for the first person in the competition and a 1/4 chance of being chosen for the 2nd position

 

please explain how you got the answer, thanks 

 

Answer 1

1)  5C2 = 5! / [3!2!] = 10 diff. groups can be selected.

 

2)  P(Mary) = 1/5.   Once Mary is chosen, it matters not who else is on the team of two.