CHAPTER 3

Question 1

what is an average?

Answer 1

• single value used to describe a set of data

Question 2

what is the mode?

Answer 2

• data value which occurs most often

Question 3

what is the median?

Answer 3

• middle value when data has been put into order

Question 4

median from a frequency table:

Answer 4

• 1(n + 1)th value

Question 5

linear interpolation- finding median formula:

Answer 5

L+ (n/2 - F/ f) x w

• L = lower boundary of class containing the median
• n = total number of values
• F = cumulative frequency of the intervals before the one containing the median
• f = the frequency of the median class interval
• w = width of the median class interval

Question 6

what is the modal class?

Answer 6

• class with the highest frequency

Question 7

what happens when data values are increased (or decreased) by the same amount/ percentage?

Answer 7

• the averages are increased/ decreased by the same percentage

Question 8

geometric mean formula?

Answer 8

n (square root) value 1 x value 2 x ….. value n

Question 9

weighted mean formula?

Answer 9

total (value x weights)/ total (weights)

Question 10

what is the range?

Answer 10

• largest - smallest value

Question 11

what is the interquartile range?

Answer 11

• upper quartile - lower quartile

Question 12

what are percentiles?

Answer 12

• when a set of data is divided into 100 equal parts

Question 13

what are deciles?

Answer 13

• when data is divided into 10 equal parts

Question 14

what is the interpercentile range?

Answer 14

• difference between two percentiles

Question 15

what is the interdecile range?

Answer 15

• difference between two deciles

Question 16

what is the standard deviation?

Answer 16

• measure of how much all of the data values deviate from the mean value or how spread out they are

Question 17

standard deviation equation?

Answer 17

square root, total xsquared/ n - (total x/n)squared

Question 18

summary statistics:

Answer 18

• summarise the data
• mean, median, mode, standard deviation, range, interquartile range

Question 19

what does a box plot represent?

Answer 19

• maximum and minimum values
• median
• upper and lower quartiles

Question 20

small outlier equation:

Answer 20

LQ - 1.5 x IQR

Question 21

large outlier equation:

Answer 21

UQ + 1.5 x IQR

Question 22

outlier for calculations involving the standard deviation:

Answer 22

x + 3 o
x= mean
o= standard deviation

Question 23

what could indicate positive skew in a set of data?

Answer 23

mean > median > mode

Question 24

what could indicate negative skew in a set of data?

Answer 24

mode > median > mean

Question 25

formula for calculating skew:

Answer 25

skew= 3(mean - median)/ standard deviation

Question 26

what can you compare in data sets?

Answer 26

• average
• measure of spread
• skew

Question 27

when comparing mode, what measure of spread should you compare?

Answer 27

• range for quantitive data

Question 28

when comparing median, what measure of spread should you compare?

Answer 28

• range
• interquartile range

Question 29

when comparing mean, what measure of spread should you compare?

Answer 29

• range
• standard deviation