Diagnostic Test in Statistics and Probability

Which of the following best describes a random variable?

• A variable whose values are finite.

• A variable whose values are infinite.

• A variable whose values are countable.

• A variable whose values are determined by chance.

Which of the following is a discrete random variable?

• the sugar content of an orange juice

• the average height of senior high school students

• the distance that a car can drive on a full tank gas

• the number of heads obtained in three tosses of a coin

Which is not a possible value of the random variable for the number of heads if two coins are tossed?

• 0

• 1

• 2

• 3

Which of the following is NOT a true statement?

• Random variables can only have one value.

• The value of the random variable could be zero.

• The probability of the value of a random variable could be zero.

• The sum of all the probabilities in a probability distribution is always equal to one.

The random variable x, representing the number of nuts in a chocolate bar has the following probability distribution. What is the mean?

• 1.9

• 2.0

• 2.1

• 2.2

Which formula gives the probability distribution shown by the table?

What is the correct formula in finding the mean of a discrete random variable X?

• μ=∑ x ∙ P(x)

What is the variance of the probability distribution?

Given that the variance of a probability distribution is 1.8, what is the correct expression that will give its corresponding standard deviation?

Which of the following describes a normal probability distribution?

• The curve is asymmetrical.

• The area under the curve is 1.

• The mean, median, mode, and variance coincide at the center.

• The width of the curve is determined by the median of the distribution.