Chapter 4 Terms & Formulas
Q1. What is a probability experiment?
A probability experiment is chance process that leads to well defined outcomes.
Q2. Define sample space
A set of all possible outcomes from a probability experiment.
Q3. What is the difference between an outcome and an event?
An outcome is a result of a single trial from a probability experiment while an event is can consist of more than one outcome.
Q4. What are equally likely events?
Equally likely events have the same probability of occurring.
Q5. What is the range of the values of the probability of an event?
Range of the values 0 to 1 inclusive
Q6. When an event is certain to occur, what is its
The probability when an event is certain is: 1
Q7. If an event cannot happen, what value is assigned to its probability?
When an event can not happen, the value is assigned is: 0
Q8. What is the sum of the probabilities of all the outcomes in a sample space?
The sum of all the outcomes in a sample space is: 1
Q9. If the probability that it will rain tomorrow is 0.20, what is the probability that it won’t rain tomorrow? Would you recommend taking an umbrella?
The probability that it won't rain tomorrow is 0.80. The probability that it won't rain is 0.80 more than the probability that it will rain - 0.2, so an umbrella won't be needed. Although it would be nice to have one in your car just in case - just saying.
Q10. Define mutually exclusive events.
If they cannot occur at the same time. (I.E. They have no outcomes in common).
Measures of average are also called
central tendency and include the mean, median, mode, and midrange.
The measures that determine the spread
of the data values are called
measures of variation, or measures of dispersion. These
measures include the range, variance, and standard deviation.
Finally, another set of measures is necessary to describe data. These measures are
called measures of position.
They tell where a specific data value falls within the data set
or its relative position in comparison with other data values. The most common position
measures are percentiles, deciles, and quartiles. These measures are used extensively in
psychology and education. Sometimes they are referred to as norms.
A statistic is
a characteristic or measure obtained by using the data values from a sample.
A parameter is
a characteristic or measure obtained by using all the data values from a
The mean is
the sum of the values, divided by the total number of values. The symbol
represents the sample mean.
The median is
the midpoint of the data array. The symbol for the median is MD.