Unit 1 - Analysis of Data : Stem and Leaf Diagrams and Box Plots

Question 1

How to find the median position

Answer 1

Position of the median = (n+1)/2
n = number of data items

Question 2

Q0

Answer 2

The minimum value

Question 3

Q1

Answer 3

Lower quartile
(n+1)/2 where n = number of units before the median value

Question 4

Q2

Answer 4

median middle
(n+1)/2 where n = total number of units

Question 5

Q3

Answer 5

Upper quartile
(n+1)/2 where n = number of units after the median value
the position number is the same as Q1

Question 6

Q4

Answer 6

The maximum value

Question 7

Outliers

Answer 7

Outliers are any results which are classed as rare

Lowest = Q1 - 1.5 x (Q3 - Q1)
Highest = Q3 + 1.5 x (Q3 -Q1)

Question 8

IQR

Answer 8

Q3 - Q1

Question 9

How to find mean of a frequency distribution

Answer 9

First find the midpoint of interval is there is one, then multiply the frequency by the midpoint to find fx. Add all fx values together then put it over the sum of all frequency values.

Question 10

Frequency distribution formula

Answer 10

Σfx ÷ Σf

Question 11

Finding the median of grouped data

Answer 11

Find the sum of the frequency and divide it by two to find the position of the median. Find which group the median would be in based on cumulative frequency. Subtract the beginning of the group frequency (number at bottom left of box) from the median position. Put that number over the frequency of the group. Then multiply that by the difference between the group and add on the start of the group.

(Position of the median - beginning of cum. freq. for that group/ frequency of that group) x deference between group + beginning of group value