Probability Test Replacement Questions
Name____________________ Class___________ Date__________ Mark____________
1.
In a factory producing LEDs, the QC department determined that, in general, the defective
rate is 2%. In a batch of 1000 LEDs if 50 are taken randomly as a sample what is the
probability that at most 3 defective LEDs are found?
(2)
2.
Eight fair coins are flipped at the same time. What is the probability of getting exactly four
heads and four tails? Use one row in Pascal’s Triangle to describe the outcomes. (2)
3.
Students X and Y are doing a talent quiz. They will choose one question each from a question
bank containing 6 type A and 5 type B questions. What is the probability of the event that X
and y get different questions?
(2)
4. A box contains 7 red and 3 blue balls. Three are drawn one after another randomly without
replacement. What is the probability that:
(a) at most two of the three are red?
(b) the third one is a red on the condition that the first and the second are different in colour?
(3)
5. The eight members of a club pose in one line for a club photo. If they line up randomly, what
is the probability that
(a) either Holina will be the first or Baolina will be last?
(b) Holina will first and Baolina will not be last?
(2)
6. Mr. H insured his house and car. In any one year the P of the house burning is 0.01 and the P
of the car being stolen is 0.05. For any one year determine the P of the following events.
(a) The house burns and the car is stolen.(b) The house burns or the car is stolen.(but not both)
(c) Neither the house burns nor the car is stolen.
(3)
7. Sixteen animals need to be transported from Toronto to Kingston in a big truck with three
compartments that can hold 3, 5, and 8 animals respectively. Among the animals there are one
wolf, one rabbit and fourteen cows and bulls. The wolf won’t bother the big animals but may
eat the rabbit. Find the probability on the luck for the rabbit’s not being hurt by the wolf if the
animals are distributed into the three compartments randomly.
Answers:
1. 0.9852
2. 27.3438%
3. If different types of questions 6/11; If different questions and
repetition allowed, P(11, 2)/121 4.a) 70.83% b) 3/4
5.a) 23.2143%
b) 10.7143
6.a) 0.0005 b) 0.0590
c) 0.9405
7. 474474/720720=79/120