Question

. A particular starship has 40 Vulcans, 60 Humans, and 25 Andorians. They are selected in random order to test a rare drug which has just been discovered (with replacement). Find the probability that at least 4 must be selected in order to obtain an Andorian

Answer 1

SOLUTION:

From given data,

A particular starship has 40 Vulcans, 60 Humans, and 25 Andorians. They are selected in random order to test a rare drug which has just been discovered

40 Vulcans

60 Humans

25 Andorians

Total = 40+60+25 = 125

Find the probability that at least 4 must be selected in order to obtain an Andorian

we have 25 Andorians.

P(A) = 25 / 125 = 0.2

we know that,

Law of the complement:

P(not A) = 1 - P(A)

P(not A) = 1 - (25 / 125) = 4/5 (or) 1 - 0.2 = 0.8

(4/5)*(4/5)*(4/5) = 64/125

(or)

(0.8)*(0.8)*(0.8) = 0.512