Question

each ticket in a lottery contains a single hidden letter. among all the tickets 50% contain w 40% contain i and 10% contain n how many tickets should you expect to buy in order to be able to spell the word win

Answer 1

Let $N=$ the number of tickets in a lottery.

At first I may choose only the tickets with the letter w and the tickets with the letter i. There are $0.5N+0.4N$ such tickets. After that the next ticket will be with the letter n.

Then I should buy  $0.5N+0.4N+1=0.9N+1$ to be able to spell the word win.