Given, in a relay race, there are five teams A, B, C, D and E.

So, total number of teams = 5

a. A, B and C finish first, second and third, respectively i.e. 3 teams will win from five teams

Now, total number of order = ⁵P₃ = 5!/(5 - 3)! = = 5!/2! = 120/2 = 160

Now, total number of order in which A, B and C finish first, second and third, respectively i.e. (ABC) = 1

So, P(A, B and C finish first, second and third, respectively) = 1/60

b. Let M is the event that A, B and C are the first three in any order.

So, M = {ABC, ACB, BAC, BCA, CAB, CBA}

Hence, total order = 6

Now, P{A, B and C are first three to finish (in any order)} = 6/60 = 1/10