A club has 15 members and needs to choose 2 members to be co-presidents. In how many ways can the club choose its co-presidents?​

105

Explanation:

Since we are choosing 2 out of 15 members, then the formula to use will be the combination formula which will be:

= n! /r! (n - r)!

where,

n = total members = 15

r = number of items to choose = 2

Slotting this into the formula will give:

= n! /r! (n - r)!

= 15!/2! (15-2)!

= 15!/2! 13!

= (15 × 14) / (2 × 1)

= 105

The club can choose the co-president in 105 ways.

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good question. i'll be looking into that. (this is a joke sir)