A thumb tack is tossed until it ﬁrst lands with its point down, at which time no more tosses are made. On each toss, the probability of the tack's landing point down is $1 / 3$
(a) What is the probability that exactly ﬁve tosses are made?
(b) What is the expected number of tosses?

Question

A thumb tack is tossed until it ﬁrst lands with its point down, at which time no more tosses are made. On each toss, the probability of the tack's landing point down is $1 / 3$ 
(a) What is the probability that exactly ﬁve tosses are made? 
(b) What is the expected number of tosses?

Quizplus · Accepted Answer

The Answer of A thumb tack is tossed until it ﬁrst lands with its point down, at which time no more tosses are made. On each toss, the probability of the tack's landing point down is $1 / 3$ 
(a) What is the probability that exactly ﬁve tosses are made? 
(b) What is the expected number of tosses?

A Thumb Tack Is Tossed Until It ﬁRst Lands with Its