MBA Exam undefined

An urn contain 9 blue, 7 white and 4 black balls. If 2 balls are drawn at random, then what is the probability that only one ball is white ?

1) 71/190
2) 121/190
3) 91/190
4) 93/190
5) None of these

Read Solution (Total 3)

what is the answer...
11 years agoHelpfull: Yes(0) No(0)

Method-I
No. of ways to succeed = 7*13 =91

No. of random pairs = 20C2 = 190

P(one white) = 91/190

Method-II
P(2 white) = 7C2/20C2 = 21/190

P(2 non-white) = 13C2/20C2

P(1 white) = 1-[(21+78)/20C2] = 1-99/190 = 91/190
9 years agoHelpfull: Yes(0) No(0)
(7c1×13c1)÷20c2=91÷190
8 years agoHelpfull: Yes(0) No(0)

MBA Other Question

A bag contains 3 white and 2 red balls and a box contains only 1 white ball. A fair coin is tossed. If heads appears, then 1 ball is drawn at random from the bag and placed in the box and if tails appears, then 2 balls are drawn at random from the bag and placed in the box. 1 ball is now drawn at random from the box. What is the probability that it is white?

1) 13/30
2) 23/30
3) 19/30
4) 2/3
In
a school, 100 students were offered Hindi as an optional subject and 70
French and Sanskrit each. Of these, 63 offered Hindi only, 47 French
only, 12 Hindi and French only and 6 French and Sanskrit only.The number of students who were offered all the three subjects is1. 102. 93. 64. 55. 4

1) 1
2) 2
3) 3
4) 4
5) 5