Stem and Leaf Plot Width - Statistics

Question

Twenty boys and twenty girls took part in a reaction timing experiment. Their results measured to the nearest one hundredth of a second.

 

Girls:

0.22 - 0.19 - 0.21 - 0.16 - 0.18 - 0.21 - 0.18 - 0.24 - 0.16 - 0.22 - 0.19 - 0.19 - 0.25 - 0.22 - 0.22 - 0.25 - 0.17 - 0.22 - 0.17 - 0.22

 

Boys:

0.14 - 0.16 - 0.20 - 0.15 - 0.22 - 0.09 - 0.16- 0.23 - 0.19 - 0.11 - 0.16 - 0.21 - 0.15 - 0.22 - 0.23 - 0.18 - 0.23 - 0.18 - 0.19 - 0.16

 

Question: Starting with a stem of 0.08 seconds and a width of 0.02 seconds, draw a back to back stem and leaf plot.

 

What does the question mean by the width? I don't even know how to begin here...

Answer 1

First of all, the wanton use of - to separate all of the individual data times is very poor in a mathematical context.A FAR BETTER practice would be to simply put 2 spaces between each data item (which to me would be more readable than using commas as separators).

 

It seems to me that what is wanted is a frequency table:

For Boys it would be

Time    freq

.08       1     ⇐counting the single .09 datum; width means tabulate .08 & .09 together

.10       1     ⇐counting the single .011 datum.

.12       0

.14       3     ⇐counting the one 0.14 & two 0.15 data   

etc.