Hello

I need helo with this problem

Flip n=8 fair coins and remoev all the headss that came up.flip the other remaining until each has come up heads.We want to find the pmf of Y the number of trials needed.Let Xi be the number of flips required to observe heads on coin i,i=1,2,3...8 then Y=max(X1,X2...X8).

I want to show that P(Y<=y)=[1-(1/2)^y]^8

I know the formula but i dono from where to get the 1-(1/2)^y

i got the pmf of Xi and it is (1/2)^x then what shall i do?

Thanks everyone