SaveYour Earth, anNGO, conducted a survey asking subjects whether they are a member of anyNGOworking for environmental protection and whether they would be willing to purchase a sapling. Table 4.4 shows the results.

(a) Estimate the probability that a randomly selected adult is a member of an NGO.

(b) Show that the estimated probability of being willing to plant a tree is (i) 0.238, given that the person is a member of an NGO; (ii) 0.1407, given that the person is not a member of an NGO.

(c) Show that the estimated probability that a person is both a member of an NGO and willing to purchase a sapling is 0.0564 (i) directly using the counts in the table,

(ii) using the probability estimates from

(a) and (b).

(d) Show that the estimated probability that a person answers yes to both questions or no to both questions is 0.712.

TABLE 4.4 Willing to Plant a Tree Yes No Total Member of Yes 50 160 210 the NGO No 95 580 675 Total 145 740 885