The report "Progress for Children" (UNICEF, April 2005) includedthe accompanying data on the percentage of primary-school-agechildren who were enrolled in school for 19 countries in NorthernAfrica and for 23 countries in Central Africa.
Northern Africa| 54.6 | 34.3 | 48.9 | 77.8 | 59.6 | 88.5 | 97.4 | 92.5 | 83.9 | 96.9 | 88.9 |
| 98.8 | 91.6 | 97.8 | 96.1 | 92.2 | 94.9 | 98.6 | 86.6 | | | |
Central Africa| 58.3 | 34.6 | 35.5 | 45.4 | 38.6 | 63.8 | 53.9 | 61.9 | 69.9 | 43.0 | 85.0 |
| 63.4 | 58.4 | 61.9 | 40.9 | 73.9 | 34.8 | 74.4 | 97.4 | 61.0 | 66.7 | 79.6 |
| 98.9 | | | | | | | | | | |
We will construct a comparative stem-and-leaf display using thefirst digit of each observation as the stem and the remaining twodigits as the leaf. To keep the display simple the leaves will betruncated to one digit. For example, the observation 54.6 would beprocessed as
54.6 ? stem = 5, leaf = 4 (truncated from 4.6),
the observation 96.1 would be processed as
96.1 ? stem = ? , leaf = ? (truncated from 6.1)
and the observation 35.5 would be processed as
35.5 ? stem = ? , leaf = ?(truncated from 5.5).
The resulting comparative stem-and-leaf display is shown in thefigure below.
Comparative stem-and-leaf display for percentage of childrenenrolled in primary school.
Stem: Tens
Leaf: Ones| Central Africa | | Northern Africa |
|---|
| 4854 | 3 | 4 |
| 035 | 4 | 8 |
| 838 | 5 | 49 |
| 6113913 | 6 | |
| 943 | 7 | 76 |
| 5 | 8 | 8386 |
| 87 | 9 | 7268176248 |
From the comparative stem-and-leaf display we can see that there isquite a bit of variability in the percentage enrolled in school forboth Northern and Central African countries and that the shapes ofthe two data distributions are quite different. The percentageenrolled in school tends to be higher in Northern African countriesthan in Central African countries, although the smallest value ineach of the two data sets is about the same. For Northern Africancountries the distribution of values has a single peak in the 90swith the number of observations declining as we move toward thestems corresponding to lower percentages enrolled in school. ForCentral African countries the distribution is more symmetric, witha typical value in the mid 60s.
How many individual stem-and-leaf displays are represented by thecomparative stem-and-leaf display?
-one
-two
-three
-It can't be represented as simple stem-and-leaf display.
