Suppose that starting at a certain time batteries coming off

Suppose that, starting at a certain time, batteries coming off an assembly line are examined one by one to see whether they are defective (let D = defective and N = not defective). The chance experiment terminates as soon as two nondefective batteries have been obtained.

(a) Let A denote the event that at most two batteries must be examined to terminate the chance experiment. What outcomes are contained in A?

A = {NN}A = {NN, DNN, NDN}    A = {DD, NDD, DND}A = {NN, DNN, NDN, DDNN, DNDN, NDDN}A = {DD, NDD, DND, NDN, NNDD, NDND, DNND}

(b) Let B be the event that exactly four batteries must be examined before the chance experiment terminates. What outcomes are in B?

B = {DDNN, NDDN, DNND, DNDN, NDND, DNND, NNNN, DDDD}B = {DN, ND, DD, NN}    B = {DDNN, NDDN, DNND, DNDN, NDND, DNND}B = {NNDD, DNND, NDND}B = {DDNN, NDDN, DNDN}

(c) What can be said about the number of possible outcomes for this chance experiment?
There are  ---Select--- a finite an infinite number of possible outcomes.

Solution

(c) What can be said about the number of possible outcomes for this chance experiment?

there are 4 + 5 = 9