Nigeria Customs Service Past Questions and Answers for Aptitude Test

Question 1: What is the probability of having an odd number in a single toss of a fair die?
(a) 1/6
(b) 1/3
(c) ½
(d) 2/3
Answer: C

Use the following information for question 2 and 3
The surname of 40 children in a class were arranged in alphabetical order,16 of the surnames begin with O and 9 of the surnames begins with A. 14 letters of the alphabet do not appear as the first letter of a surname.

Question 2: What is the probability that the surname of a child picked at random from the class begins with either O and A?
(a) 5/8
(b)7/8
(c)9/16
(d)14/25
Answer: A

Question 3: If more than one surname begins with a letter besides A and O, how many surnames begin with the letter?
(a) 2
(b) 3
(c) 4
(d) 6

Answer: B

The table gives the score of a group of students in an English language test.

Question 4: If a student is chosen at random from the group, what is the probability that he scored at least 6 marks?
(a) 3/20
(b) 1/5
(c) ¼
(d) 3/10
Answer: C

Question 5: What is the probability that three customers waiting in a bank will be served in the Sequence of their arrival at the bank?
(a) 1/6
(b) 1/3
(c) ½
(d) 2/3
Answer: C

Question 6: The probability that Kodjo and Adoga pass an examination are ¾ and 3/5 respectively. Find the probability of both boys failing the examination.
(a) 1/10
(b) 3/10
(c) ½
(d) 2/3
Answer: A

Question 7: The mean of 20 observations in an experiment is 4. If the observed largest value is 23, Find the mean of the remaining observations.
(a) 4
(b) 3
(c) 2.85
(d) 2.60
Answer: A

Question 8: A group of eleven people can speak either English or French or both. Seven can speak English and six can speak French. What is the probability that a person chosen at random can speak both English and French?
(a) 2/11
(b) 4/11
(c) 5/11
(d) 11/13
Answer: B

If events X and Y are mutually exclusive, P(X) = 1/3 and P(Y) = 2/5, Use the information to answer questions 9 & 10.

Question 9: P (X n Y) is
(a) 0
(b) 2/15
(c) 4/15
(d) 11/15
Answer: A

Question 10: P (X u Y) is
(a) 0
(b) 2/15
(c) 4/15
(d) 11/15
Answer: A

11: A box contains 2 white and 3 blue identical marbles. If two marbles are picked at Random, one after the other, without replacement, What is the probability of picking two marbles of different colours?
(a) 2/3
(b) 3/5
(c) 2/5
(d) 7/20
Answer: D

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