STATISTICS & PROBABILITY PRE-TEST 3

What do you call a random variable with possible values that form a finite or countable set?

• continuous

• discrete

• finite

• infinite

What term is used to describe the average value of a discrete random variable over numerous trials of an experiment?

• mean

• probability

• standard deviation

• variance

Which of the following represents the amount of spread, dispersion, or variability of the items in a distribution?

• mean or expected value

• median and mode

• outcomes and probability distribution

• variance and standard deviation

Which of the following is also equal to the square root of the variance?

• mean

• median

• probability

• standard deviation

How would you interpret a very small variance or standard deviation but not equal to zero?

• The values of the random variables are farther from the mean.

• The values of the random variables are nearer to the mean.

• The values of the random variables are equal to the mean.

• The values of the random variables have no relationship with the mean.

Which of the following shows most likely the largest possible variance or variability?

• number of girls in a randomly selected three-child family

• number of newborn babies per minute.

• number of Oreo cookies inside a 133 grams pack from different

  branch of 711 stores

• number of patients who are positive with COVID-19 in different

  hospitals

Which of the following data shows most likely the smallest possible variance or variability?

• number of books in different branch of National Bookstore

• number of books inside a pack bag of grade 11 students

• number of books inside the library of different universities

• number of books inside the library of different households

What formula is described by σ² = ∑[x² * P(x)] − u²?

Which of the following is NOT a property of the variance?

• The variance is not equal to the standard deviation.

• A small variance means that the distribution of the random variable is narrowly concentrated around the mean.

• A large variance means that the distribution is spread out, with some chance of observing values at some distance from the mean.

• The value of the variance is less than zero.

Which of the following represents the mean value of a discrete random variable?

• Expected value

• Median

• Standard deviation

• Standard deviation