Question

Let g be a friendship networl of a class of 50 students. If there are three groups in the network consisting of 25,20 and 5 students, respectively, such that none of tbe students kn any group has friends in the other two groups how many friendships are possible to make g connected

Answer 1

Answer:

500

Step-by-step explanation:

So there are 3 groups 25, 20 and 5, we will calculate combinations of friendship in every group separately since the students in any group have no friends in other groups.

Formula to be use is

(n(n-1)/2)

where n is number of people in the group.

1) 25

25(25-1)/2 = 300

2) 20

20(20-1)/2 = 190

3) 5

5(5-1)/2 = 10

Further explaining:

You can also count the combination by sequentially adding till (n-1)

like in group having 5 people

1+2+3+4 = 10 friendships possible

g = 300 + 190 + 10

   =500