GRE Exam Numerical Ability Permutation and Combination

In a box of 10 electrical parts, 2 are defective.
(a) If one part is chosen randomly from the box, what is the probability that
it is not defective?
(b) If two parts are randomly chosen from the box, without replacement,
what is the probability that both are defective?

Read Solution (Total 2)

(a) 8/10 = 4/5
(b) (2/10)*(1/9) = 1/45
14 years agoHelpfull: Yes(4) No(5)

8C1=8/10
(2c1*1c1)/=2/45
10 years agoHelpfull: Yes(0) No(3)

GRE Other Question

If an integer is randomly selected from all positive 2-digit integers
(i.e., the integers 10, 11, 12, . . . , 99), find the probability that the
integer chosen has
(a) a "4" in the tens place
(b) at least one "4"
(c) no "4"� in either place Lin and Mark each attempt independently to decode a message. If the
probability that Lin will decode the message is 0.80 and the probability
that Mark will decode the message is 0.70 find the probability that
(a) both will decode the message
(b) at least one of them will decode the message
(c) neither of them will decode the message