Question

A darts player knows that her chances of a bullseye on any throw is 0.1. Find the number of turns she would need to ensure a probability of 0.9 of scoring at least 1 bullseye

Answer 1

9 throws would give a probability of 0.9 that at least one bullseye was hit. each turn consists of 3 darts which is 3 throws (usually). so she would need 3 turns.

Answer 2

least one bulls eye means "not no bulls eyes" the probability you get no bulls eyes in n tries is
\[.9^n\] so the probability you get at least one bulls eye in n tries is
\[1-.9^n\]

Answer 3

therefore your job is solving
\[1-.9^n\geq .9\] for n

Answer 4

i get about 22

Answer 5

satellite73 is right - I guess I am not as good at probability as I thought :-(

Answer 6

Thank you satellite!

Answer 7

yw