Math 104 - Exam 3
If it is possible for events A and B to occur simultaneously, then P(A or B) =
P(A) + P(B) - P(A and B)
If the odds in favor of event E are a to b, then the probability of the event, P(E), is given by the formula (BLANK).
P(E) = a divided by a + b
If the occurrence of one event has an effect on the probability of another event, the events are said to be (BLANK). For such events, P(A and B) = (BLANK).
dependent P(A) x P(B given that A occurred)
Because P(E) + P(not E) = 1, then P(not E) = (BLANK) and P(E) = (BLANK)
1 - P(E) 1 - P(not E)
In a normal distribution, approximately (BLANK) % of the data items fall within 1 standard deviation of the mean, approximately (BLANK) % of the data items fall within two standard deviations of the mean, and approximately (BLANK) % of the data items fall within 3 standard deviations of the mean.
68 95 99.7
The odds in favor of E can be found by taking the probability that (BLANK) and dividing by the probability that (BLANK).
E will occur; E will not occur
T/F: "And" probabilities can always be determined using the formula P(A and B) = P(A) x P(B).
False
T/F: A data set can contain more than one median, or no median at all.
False
T/F: A sample is the set of all the people or objects whose properties are to be described and analyzed by the data collector.
False
T/F: According to the National Center for Health Statistics, the lifetime odds in favor of dying from heart disease are 1 to 5, so the probability of dying from heart disease is 1/5.
False
T/F: If one or more data items are much greater than the other items, the mean, rather than the median, is more representative of the data.
False
T/F: Measures of dispersion get smaller as the spread of data items increases.
False
T/F: One disadvantage of a stem-and-leaf plot is that it does not display the data items.
False
T/F: Probability problems with the word "or" involve more than one selection.
False
T/F: The probability of A or B can always be found by adding the probability of A and the probability of B.
False
T/F: The probability that an event will not occur is equal to the probability that it will occur minus 1.
False
T/F: When finding the mean, it is necessary to arrange the items in order.
False
The z-score for a data item in a normal distribution is obtained using: z-score = data item - standard deviation divided by mean.
False
A score in the 50th percentile on a standardized test is the median.
True
T/F: A call-in poll on radio or television is not reliable because the sample is not chosen randomly from a larger population.
True
T/F: A deception in the visual display of data can result by stretching or compressing the scale on a graph's vertical axis.
True
T/F: In a normal distribution, the z-score for the mean is 0.
True
T/F: Measures of dispersion are used to describe the spread data items in a data set.
True
T/F: Numbers representing what is average or typical about a data set are called measures of central tendency.
True
T/F: P(B/A) is the probability that event B occurs if the sample space is restricted to the outcomes associated with event A.
True
T/F: The mean, median, and mode of a normal distribution are all equal.
True
T/F: The odds against E can always be found by reversing the ratio representing the odds in favor of E.
True
T/F: The probability that an event happens at least once can be found by subtracting the probability that the event does not happen from 1.
True
T/F: The sum of the deviations from the mean for a data set is always zero.
True
The probability of event B, assuming that event A has already occurred is called the (BLANK) probability of B, given A. The probability is denoted by (BLANK).
conditional P(B/A)
If data values are listed in one column and the adjacent column indicates the number of times each value occurs, the data presentation is called a/an (BLANK BLANK).
frequency distribution
If the midpoints of the tops of the bars for the data presentation in Exercise 4 are connected with straight lines, the resulting line graph is a data presentation called a/an (BLANK BLANK). To complete such a graph at both ends, the lines are drawn down to touch the (BLANK BLANK).
frequency polygon horizontal axis
If the data presentation in Exercise 2 is varied by organizing that data into classes, the data presentation is called a/an (BLANK BLANK BLANK). If one class in such a distribution is 80-89, the lower class limit is (BLANK) and the upper class limit is (BLANK).
grouped frequency distribution 80 89
Data can be displayed using a bar graph with bars that touch each other. This visual presentation of the data is called a/an (BLANK). The heights of the bars represent the (BLANK) of the data values.
histogram frequencies
If the occurrence of one event has no effect on the probability of another event, the events are said to be (BLANK). For such events, P(A and B) = (BLANK).
independent P(A) x P(B)
A z-score describes how many standard deviations a data item in a normal distribution lies above or below the (BLANK).
mean
The sum of all the data items divided by the number of data items, is the measure of central tendency called the (BLANK).
mean
The measure of central tendency that is the data item in the middle of ranked, or ordered, data is called the (BLANK).
median
The measure of central tendency that is found by adding the lowest and highest data values and dividing the sum by 2 is called the (BLANK).
midrange
A data value that occurs most often in a data set is the measure of central tendency called the (BLANK).
mode
If it is impossible for events A and B to occur simultaneously, the events are said to be (BLANK). For such events, P(A or B) = (BLANK).
mutually exclusive P(A) + P(B)
If n data items are arranged in order, from smallest to largest, the item in the middle is the value in (BLANK) position.
n + 1 over 2
If n% of the items in a distribution are less than a particular data item, we say that the data item is in the nth (BLANK) of the distribution.
percentile
A sample obtained in such a way that every member of the population has an equal chance of being selected is called a/an (BLANK) sample.
random
The difference between the highest and lowest data values in a data set is called the (BLANK).
range
A data presentation that separates each data item into two parts called a/an (BLANK BLANK BLANK BLANK).
stem-and-leaf plot
The probability of an event occurring at least once is equal to 1 minus the probability that (BLANK).
the event does not occur
