Question

An urn contains 20 red balls and 50 blue balls. Two are chosen at random, one after the other, without replacement. (Round your answers to one decimal place.) (a) Use a tree diagram to help calculate the following probabilities: the probability (as a %) that both balls are red % the probability (as a %) that the first ball is red and the second is not % the probability (as a %) that the first ball is not red and the second is red % the probability (as a %) that neither ball is red % (b) What is the probability (as a %) that the second ball is red? % (c) What is the probability (as a %) that at least one of the balls is red? %

Answer 1

20 red balls so blue balls Total = 20+50=70 balu Two e Chosen without replacement R.-Red B- Blue RR >RB R »BR B BB both balls P(RR) = are red 20 yo 19 89 0.0787 17687) not first ball is red and second is PIRB) 50 X 70 69 0-2070 20- 77 first ball not sed and second is red P(BR) = 50 70 02070 * 20 69 207D neither ball is red ti P(BB) =50 205072 70 og 50.72 L

b) a(second ball is red) =? Boba P(RR) + P(BR) 50 120 70 0.2857 XII 1380 4830 4 69 60 28.57% U atleast one ball is red probability = P(RR) +(RB) + P(BR) | Plneither red) te PlBB) 50x49 =l-a50724 70x69 = 0.49276 ५१.२8 -