from walpole 5.61

Suppose the probability is 0.8 that any given person wll believe a tale about the transgressions of a famous actress.

a) the sixth person to hear this tale is the forth one to believe it ?

b) what is the probability that the thrd person to hear this tale is the first one to believe it ?

i know p= 0.80 and q = 1- 0.8=0.20

but how should i apply the above to the questions ?

i don't even know how many people are listening to the tale.

pls explain.