A student is randomly selected in a university Event A denot

A student is randomly selected in a university. Event A denotes that the student uses MasterCard, while event B denotes that the student uses Visa Card. Given that P(A) = 0.48, P(B) =0.42, P(AnB) = 0.21, which option defines the probability that the selected student has neither of the cards. P(A\'nB\') = 0.69 P(AuB)\' = 0.31 P(A\'nB\') = 0.79 P(AnB)\' = 0.79 In his Final exam, a Professor permits the use of PCs on the condition that Wi-Fi is turned off. He has known that 1 out of 11 students will disobey his rule, therefore he does a random check. Find the probability that the first student to disobey (turned on Wi-Fi) was found after 13 students were checked. 0.26 0.29 0.32 0.68

Solution

7.

P(A U B)\' = 1 - [P(A) + P(B) - P(A n B)]

= 1 - (0.48+0.42-0.21)

= 0.31 [ANSWER, B]

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8.

Note that

P(X>=n) = (1-p)^(n-1)

Thus, as n = 13 here, p = 1/11,

P(X>=13) = (1-1/11)^(13-1) = 0.318630818 = 0.32 [ANSWER, C]