Question

A teacher will pick 1 student at random from 50 for the lead in a play. What is the probability of a student, Jo, of winning?

1/X, so X%

Answer 1

Answer)

Probability is given by favorable/total

Total = 50

Now teacher will pick 1 student randomly

We can pick r from n in ncr ways

Where

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

Where n! = n*n-1*n-2*n-3*n-4*n-5*....till 1

For example

5! = 5*4! = 5*4*3! = 5*4*3*2! = 5*4*3*2*1

50c1 = 50!/(1!*(50-1)!) = 50

Total = 50

Favorable = 50

So probability is 50/50 = 1 or 100%