Andy was given data to draw 3 scatter diagrams. He also decided to draw a line of best fit on each one.
501
100
50
90
XI
40
40
1X
X
80
70
30
30
60
50
20
20
10
10
40
X
30
X
20
IX
10
0
0 10 20 30 40 50 60 70 80 90 100
Diagram B
Oo
08
10
20
30
40
50
8
Diagram C
Diagram A
a) What type of correlation is shown in diagram A?
b) Which diagram shows the strongest correlation?
c) Which line of best fit should not have been drawn?
Give a reason for your answer

An annual marathon covers a route that has a distance of approximately 26 miles. winning times for this marathon are all over 2 hours. the following data are the minutes over 2 hours for the winning male runners over two periods of 20 years each. earlier period 14 12 15 22 13 10 19 13 9 14 20 18 16 20 23 12 18 17 6 13 recent period 7 11 7 14 8 9 11 14 8 7 9 8 7 9 9 9 9 8 10 8 (a) make a stem-and-leaf display for the minutes over 2 hours of the winning times for the earlier period. use two lines per stem. (use the tens digit as the stem and the ones digit as the leaf. enter none in any unused answer blanks. for more details, view how to split a stem.) minutes beyond 2 hours earlier period 0 1 2 (b) make a stem-and-leaf display for the minutes over 2 hours of the winning times for the recent period. use two lines per stem. (use the tens digit as the stem and the ones digit as the leaf. enter none in any unused answer blanks.) minutes beyond 2 hours recent period (c) compare the two distributions. how many times under 15 minutes are in each distribution