Unit 1 - Practice Quiz

ECE180 50 Questions
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1 Which of the following defines the sample space of an experiment?

A. The set of all possible outcomes.
B. The set of outcomes satisfying a specific condition.
C. The set of all successful outcomes.
D. The numerical value assigned to an outcome.

2 If set and set are disjoint (mutually exclusive), which of the following is true regarding their intersection?

A.
B.
C.
D.

3 According to De Morgan’s Laws, the complement of the union of two sets is equal to:

A.
B.
C.
D.

4 A sample space is called discrete if:

A. The probabilities of outcomes are unknown.
B. It contains uncountable outcomes.
C. It contains a finite or countably infinite number of outcomes.
D. It consists of an interval of real numbers.

5 Which of the following represents the classical definition of probability for an event , where is the total number of equally likely outcomes and is the number of favorable outcomes?

A.
B.
C.
D.

6 Which of the following is NOT a fundamental axiom of probability?

A. If , then .
B. for any event .
C. for any two events and .
D. , where is the sample space.

7 For any event , what is the relationship between and (the complement of A)?

A.
B.
C.
D.

8 The conditional probability of event given event (where ) is defined as:

A.
B.
C.
D.

9 Two events and are said to be statistically independent if:

A.
B.
C.
D.

10 If and are mutually exclusive events with and , what is ?

A. 0.0
B. 0.1
C. 0.12
D. 0.7

11 In a mathematical model of an experiment, what is the event usually defined as?

A. A random variable.
B. A subset of the sample space.
C. A single outcome.
D. The sample space itself.

12 Bayes' Theorem relates the conditional probabilities and . The formula is:

A.
B.
C.
D.

13 The Total Probability Theorem states that if events form a partition of sample space , then for any event :

A.
B. Both A and B
C.
D.

14 In Bernoulli trials, which of the following conditions must hold?

A. The probability of success changes with every trial.
B. There are only two possible outcomes (Success/Failure) in each trial.
C. The experiment is performed only once.
D. The trials are dependent on each other.

15 If a fair coin is tossed 3 times (Bernoulli trials), what is the probability of getting exactly 2 heads?

A.
B.
C.
D.

16 What is the definition of a Random Variable ?

A. A function that maps the sample space to the real line .
B. A subset of the sample space.
C. A variable that takes random values.
D. A function that maps real numbers to probabilities.

17 Which of the following is a necessary condition for a function to be a valid random variable?

A. .
B. .
C. The set must be an event (measurable) for every real .
D. The function must be continuous everywhere.

18 A random variable is called discrete if:

A. Its range is an uncountably infinite set.
B. It has a probability density function (PDF).
C. Its Cumulative Distribution Function (CDF) is continuous everywhere.
D. Its range is a countable set of values.

19 A random variable is called continuous if:

A. It is defined only for integers.
B. It can take any value within a specific interval on the real line.
C. for some constant .
D. Its CDF, , is a step function.

20 What characterizes a Mixed Random Variable?

A. Its PDF is zero everywhere.
B. It is the product of a discrete and a continuous random variable.
C. Its CDF has both jump discontinuities and continuous increasing segments.
D. It is the sum of two discrete random variables.

21 The Cumulative Distribution Function (CDF) of a random variable is defined as:

A.
B.
C.
D.

22 Which of the following is NOT a property of a Cumulative Distribution Function (CDF), ?

A. and .
B.
C. is a non-decreasing function.
D. is always continuous.

23 For a continuous random variable , the probability of a specific point outcome is:

A. Undefined
B.
C. 0
D. 1

24 If is the Probability Density Function (PDF) of a continuous random variable , then:

A.
B. must be .
C.
D. represents the probability .

25 How is the Probability Density Function (PDF) obtained from the CDF for a continuous random variable?

A. By subtraction:
B. They are unrelated.
C. By differentiation:
D. By integration:

26 For a discrete random variable , the function is called the:

A. Cumulative Mass Function
B. Probability Density Function (PDF)
C. Unit Step Function
D. Probability Mass Function (PMF)

27 If , then which of the following is true regarding their probabilities?

A.
B.
C.
D.

28 The joint probability is equivalent to:

A.
B.
C.
D.

29 In a continuous sample space, an event with probability zero:

A. Can occur, but is statistically negligible (e.g., a specific point).
B. Never occurs.
C. Is the empty set .
D. Implies the experiment is invalid.

30 If , , and , then events and are:

A. Dependent
B. Complementary
C. Independent
D. Mutually Exclusive

31 What is the Probability Mass Function (PMF) of a Bernoulli random variable with probability of success ?

A.
B.
C.
D. for

32 For a random variable , the expression in terms of CDF is:

A.
B.
C.
D.

33 The Dirac delta function is often used in the PDF of which type of random variable?

A. Mixed or Discrete (when represented in continuous notation)
B. Purely Continuous
C. Bernoulli only
D. Gaussian only

34 A function can be a valid CDF if and only if:

A.
B. It is continuous.
C. It is non-decreasing, right-continuous, .
D. It is a decreasing function.

35 Which set operation corresponds to the logical 'OR' operator for events?

A. Complement ()
B. Intersection ()
C. Union ()
D. Difference ()

36 The Law of Total Probability is useful for:

A. Calculating the mean of a random variable.
B. Finding the median of a PDF.
C. Finding the probability of an event based on a partition of the sample space.
D. Determining if two events are independent.

37 Given and , what is ?

A. 1.3
B. 0.625
C. 0.4
D. 0.3

38 A partition of the sample space is a collection of events such that:

A. They all have equal probability.
B. They are independent.
C. Their intersection is .
D. They are pairwise disjoint and their union is .

39 In the context of random variables, what does the notation imply?

A. is a function of the outcome .
B. is multiplied by .
C. is independent of .
D. is the derivative of .

40 If is a discrete random variable taking values $1, 2, 3$ with probabilities $0.2, 0.5, 0.3$, what is ?

A. 0.3
B. 0.7
C. 0.2
D. 0.5

41 Which of the following is an example of a continuous random variable?

A. The value of a roll of a die.
B. The time until a light bulb burns out.
C. The number of heads in 10 coin tosses.
D. The number of defective items in a batch.

42 If , and are mutually exclusive, what is ?

A. 0
B. 0.4
C. 0.16
D. 1

43 What is the value of for a discrete random variable?

A.
B. 1
C. 0
D. 0.5

44 In the experiment of tossing two fair coins, let be the number of heads. The range of is:

A.
B.
C.
D.

45 Relative frequency probability definition is strictly valid when:

A. The outcomes are not equally likely.
B. We cannot perform an experiment.
C. The number of trials approaches infinity.
D. The number of trials is small.

46 If and , then is:

A. A subset of A.
B. The complement of A ().
C. Equal to A.
D. An impossible event.

47 For a continuous PDF , the dimensionality of is:

A. Probability (unitless).
B. Same as the random variable's unit.
C. Undefined.
D. Inverse of the random variable's unit.

48 Which axiom prevents negative probabilities?

A. Independence axiom.
B. Additivity axiom.
C. Non-negativity axiom.
D. Normalization axiom.

49 If , then:

A. and are independent.
B. and are mutually exclusive.
C. .
D. .

50 Given a CDF , the probability is:

A.
B.
C.
D.