mahakmalik wrote:

what if we do it like this?

let us assume total tickets are 20

so 8 tickets give us vacation

and 12 are blank

so 3 have to select vacation ticket

so probability\(5c3 * ((\frac{8c1*8c1*8c1)}{20c1*20c1*20c1})\)

Hello

mahakmalik,

How it was solved above is from a formula specifically for the probability when x will occur and when not x will occur, the Bernoulli formula. The initial part of your expression selects three out of five people correctly. However, the second part of the expression is essentially the same thing except for the probability for not x, which is an equally important part as anything else. Thus, extend the expression with the probability of not x:

\(5c3 * ((\frac{8c1*8c1*8c1)}{20c1*20c1*20c1})*(\frac{12c1*12c1}{20c1*20c1}))\)

Then, you have a identical formula but with bigger numbers, which leads to the same answer. Hope this helps!

Kr,

Mejia