Ch 2 Questions (add yours here)

How do you find the midpoint? (ak)

(lower class limit) + (upper class limit)/2

NP- frequency- 4649 relative frequency- .11 what is the angle?

.11 (360) = 40

What is the five number summary for a box plot? (AB)

1. Minimum 2. First Quartile (Q1) 3. Median (Q2) 4. Third Quartile (Q3) 5. Maximum

The goals per game by a soccer team represent the first quartile for the all teams in a league. What can you conclude about the teams goals scored per game? (NJ)

25% of all teams in the league scored less goals per soccer team

What would the class width be with the max being 450, the min being 59, and the number of classes being 7?(HG)

55.86--- 56

What do you use when you have a qualitative data set? (MG)

A pie chart

Lurking variable(NM)

A variable other than x and y that simultaneously affects both variables, accounting for the correlation between the two.

define stem and leaf plot -KW

A way to display quantitative data. Stem and leaf plots are examples of exploratory data analysis.

What is a z-score? (BM)

A z-score represents the number of standard deviations, given the value (x) falls from the mean.

The goals scored per game by a soccer team represent the first quartile for all teams in a league. What can you conclude about the team's goals scored per game? (AS)

About 120min

How do you find the average (PD)

Add up all of your number Divide by how many numbers you have

KL In terms of displaying data, how is a stem-and-leaf plot similar to a dot plot?

Both plots can be used to identify unusual data values. Both plots can be used to determine specific data entries. Both plots show how data are distributed.

(JR) In terms of displaying data, how is a stem-and-leaf plot similar to a dot plot?

Both steam-and-leaf plot and the dot plot allow you to see how data are distributed, to determine specific data entries, and to identify unusual data values.

KL Use the given minimum and maximum data entries and the number of class to find the class width: min = 12, max = 88, 6 classes

Class width: (88-12)/6=13

KR- USe the frequency polygon to identify the class with the greatest, and the class with the least frquency.

Class with greatest frequency- 29.5-32.5 Classes with least frequency-11.5-14.5 and 38.5-41.5

AW - When you take a sample based on people or things that are already around you, that is called...

Convenience Sampling

True or False, A z-score of 4.99 is considered usual (MW)

False

True or False: Some quantitative data sets don't have medians. (BM)

False, all quantitative data sets have medians.

In a frequency distribution, the class width is the distance between the lower and upper limits of a class. (CW)

False, class width is the difference between the lower of consecutive frequencies.

True or False: You need 3 numbers to graph a box- and- whisker plot and they are: the minimum, the maximum, and the mean (EC).

False- You need 5 numbers for a box-and-whisker plot and they are the minimum, the maximum, the mean, the first quartile, and the third quartile.

Describe the relationship between quartiles and percentiles. (AS)

First quartile: 25th percentile Second quartile: 50th percentile Third quartile: 75th percentile

For a cumulative frequency graph do you start at the lower boundary of the first class or do you end with the lower boundary?EB

For a frequency graph you start at lower boundary and end at upper boundary of last class

What is the difference between a frequency histogram and frequency polygon? (KM)

Frequency histogram is labeled with lower class boundaries and a frequency polygon is labeled with class midpoints.

Define frequency (AB)

How often each value occurs in a data set.

What is the Medium (PD)

It's the middle number.

find the mean, median and mode of the data set; 26.0, 29.5, 27, 30.5, 29.5, 25, 31.5, 31.5, 33, 32, 27.5 (NJ)

Mean- 29.15 inches Median- 29.5 inches Mode- 29.5 inches

Find the Mean, Median, and Mode: 4 , 2 , 5 , 8 , 6 , 6 , 4 , 3 , 2 , 4 , 7 , 8 , 5 (RB)

Mean: 4.92 Median: 4 Mode: 4

Find the mean, median, and mode (EC): 4,2,5,8,6,6,4,3,2,4,7,8,5

Mean: 4.9231 Median: 5 Mode: 4

Find the median and mode of this data set- 8,8,2,3,7,7,2,4,5,6,5,3,2,8,8,7,3,3(IB)

Median- 5 Mode- 8

Example: Find the median of the data set: 4,6,3,2,2,1,7,9,8 (EH)

Median=4.

AW - How do you find the angle for a piece of a pie graph?

Multiply the percentage of the pie (as a decimal) by 360 degrees

KR- Use the frequency histogram to determine the number of classes, estimate the frequency of the class with the least frequency, estimate the frequency of the class with the greatest frequency, and determine the class width.

Number of classes-7 least frequency-10 greatest frequency-300 class width-10

What is the difference between a frequency polygon and an ogive? (AR)

Ogive is a plot of cumulative values, polygons are values themselves.

Difference between qualitative and quantitative data sets (ND)

Qualitative - Bar graph/Pareto or pie chart/circle graph Quantitative - Frequency distribution, Histogram, for plot, stem and leaf plot, scatter plot, time series, box plot

Which data do you have when using a stem and leaf plot? (IB)

Quantitative

frequency distribution, histogram, dot plot, stem and leaf, scatter plot, and box plot are examples of graphs for what type of data set? MH

Quantitative

Describing a data distribution (SOCCS) (KH)

S-Shape (normal or skewed) O-Outliers (gaps, yes or no) C-Center (mean or median) C-Context S-Spread (st. dev or range)

A student's score on an actuarial exam is in the 78th percentile. What can you conclude about the student's exam score? (VM)

The student scored higher than 78% of the students who took the actuarial exam. (VM)

(JR) True or False; if false rewrite the statement as true: A data set can have the same mean, median, and mode.

True

(T or F) The midpoint of a class is the sum of its lower and upper limits divided by two RJM

True

True Or False: Some Quantitative sets don´t have medians. (RB)

True

True of False? Class boundaries are used to ensure that consecutive bars of histograms touch. (AR)

True

True or False, A z-score of -6.45 i considered very unsual (MW)

True

class boundaries are used to ensure that consecutive bars of the histogram touch. (CW)

True

True or false? A z-score of 1.99 is considered usual. (ET)

True. If it is 2 or less it is considered usual.

True or false? A z-score of -2.5 is considered very unusual. (ET)

True. If it is less than -2 it is considered very unusual.

What is a weighted average ? (JG)

Weighted average is a method of computing a kind of arithmetic mean of a set of numbers in which some elements of the set carry more importance than others.

NT- Describe the difference between calculation of population standard deviation and that of sample standard deviation.

When calculating the population standard deviation, you divide the sum of the squared deviations by N, then take the square root of that value. When calculating the sample standard deviation by n - 1, then take the square root of that value.

When do you use a back to back stem plot? (MG)

When comparing data

Why should the number of classes in a frequency distribution be in between 5 and 20(NM)

it can other times be difficult to identify patterns

Find the mean, median, mode, and range of the data set below.(JG) 46, 31, 86, 31, 94, 78, 31

mean-56.7 median-46 mode-31 Range-63

Fractiles (HG)

numbers that partition, or divide, an ordered data set into equal parts

sigma (mk)

population standard deviation

How do you find the range of your data? (KH)

range= max-min

T or F? the class width is the distance between the lower and upper limits of a class -KW

true

True or False - A z-score of 1.99 is considered usual (sj)

true

True or False - The mean and median of a data set are both fractiles (sj)

true

JM what boundaries do you use for horizontal and vertical scale

upper class boundaries and cumulative frequency

What represents the number of standard deviations a given value x falls from the mean? MH

z-score

What does a frequency distribution table show? (ak)

classes or intervals of data entries with a count of the number of entries in each class

NP- true or false? dot plots are used for qualitative data sets

false. dot plots are used for quantitative data sets

Why should the number of classes in a frequency distribution be between 5 and 20? RJM

It might be hard to detect patterns if it is any different

NT- Explain how to find the range of a data set. What is an advantage of using the range as a measure of variation? What is a disadvantage?

The range is the difference between the max and min values of a data set. The advantage of the range is that it is easy to calculate. The disadvantage is that it uses only two entries from the data set.

A salesperson at a company sold $6,903,435 of hardware equipment last year, a figure that represented the eighth decile of sales performance at the company. What can you conclude about the salesperson's performance? (VM)

The salesperson sold more hardware equipment than 80% of the other sales people. (VM)

Explain the relationship between variance and standard deviation? (mk)

The standard deviation is the positive square root of the variance. Because squared deviation can never be negative, the standard deviation and variance can never be negative.

Jm Class width=

class range/number of classes

Outlier (EH)

When you have data that skews(messes up) your measures of central tendency.

X bar (ND)

X bar is the mean, you find the mean by adding up all numbers and dividing by the number of numbers Ex. 10, 3, 5, 11, 25, 40, 55, 60, 8, 100 10 + 3 + 5 + 11 + 25 + 40 + 55 + 60 + 8 + 100 = 317/10 = 31.7

How do you find class width? (KM)

You divide your range by class number.

How to you find the z score? EB

You subtract the mean and then divide that by the standard deviation