AP Statistics 3.1 Exploring Data
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AP Statistics: Exploring Data Drill 3, Problem 1. What does this information tell us?
|AP Statistics||Exploring Data|
|Exploring Data||Summarizing Distributions of Univariate Data|
We're given a single row from a stem and leaf plot, and we need to interpret it to figure
out which of our answer choices is true.
Remember that in a stem and leaf plot, the
stem is typically the tens value, and the leaves are the individual ones place values.
From this row, we know that the values in our stem and leaf plot are:
30, 30, 30, 34, 35, 38, 39, and 39. Now we can answer the question.
Answer choice A says that the median is 34.5. To find the median, we just find the middle
value of all of the data. But wait a second... we only know one row of values, and we don't
know the others. There could be any number of values in the
10's place, or 40's place...or anywhere. We simply don't know.
So we can eliminate answer choice A. Answer choice B wants us to find the mode,
or the most frequently occurring value in the data set.
But again, we don't know the other values in this data set...so it can't be B either.
If we take a quick scan of choices C, D, and E...
we realize we can't find the min and max in choices D and E either...
...again, because we don't know all the values of the data set.
The only answer choice left is (C).
C says that there were two 39 year olds at the science fair.
It just so happens that we have the row with people in their 30's, and it also just so
happens that there were exactly 2 people who were age 39.
Our answer is (C).