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## Representing a quantitative variable with histograms and stem plots

# Reading stem and leaf plots

AP.STATS:

UNC‑1 (EU)

, UNC‑1.G (LO)

, UNC‑1.G.2 (EK)

## Video transcript

The government created the
following stem-and-leaf plot showing the number of turtles at
each major zoo in the country. How many zoos have
fewer than 46 turtles? So what the
stem-and-leaf plot does is it gives us the first
digit in each number and essentially you could
call this the tens place. And then it gives
us the ones place. So there was only one zoo
that had four turtles. So you could view this
as 0, 0, 4, or 4 turtles. Then everything here,
the tens place, is a 1. So this number right
here is really an 11. This is a 14. This right over
here would be a 16. That's a 16, and
so forth and so on. This would be 17, 18. All of this is 23. This is 23. This is 26 because we have our
tens place right over here. This is the first digit. So let's answer the question. How many zoos have
fewer than 46 turtles? So there are no zoos that
had 40 anything turtles. And so all of these zoos
here-- so all of these had 30 something turtles,
these had 20 something turtles, these have in the teens,
this has single digits. So it's literally as many
zoos as we have listed here. So 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17. 17 zoos have fewer
than 46 turtles. Let's do another one. The buyer for a
chain of supermarkets created the following
stem-and-leaf plot showing the number of coconuts
at each of the stores. What was the smallest number
of coconuts at any one grocery store? So the buyer for a
chain of supermarkets created the following
stem-and-leaf plot showing the number of coconuts
at each of the stores. So at any one grocery store
the smallest number-- well, that's this one right over here. And remember, it's not two. We have our tens
places right over here. It's a one. So this right over
here represents 12 coconuts at that store. So we'll put 12 right over here. Let's try another one. A statistician for a
chain of department stores created the following
stem-and-leaf plot showing the number of watches
at each of the stores. How many department stores
have exactly seven watches? Well that's only this one
right over here-- 07 watches. This one, this, this,
and that one are not 7. This is representing 17
because it's in the row with 1 at the beginning. This right over
here represents 27 because it's in the row
with the 2 at the beginning. So there's only one store that
has exactly seven watches. Let's do one more. This is kind of fun. A zookeeper created the
following stem-and-leaf plot showing the number of tigers at
each major zoo in the country. How many zoos have
more than 24 tigers? So we can ignore the
zeros and the teens and we get in the 20s. This is 25. So that meets the criteria. And then you go to 28, 29. So all of these in the 30s and
all of these right over here. This 3, 0-- this
doesn't mean 0 tigers. This is 30 tigers. This is 40 tigers. So we count 1, 2, 3,
4, 5, 6, 7, 8, 9, 9 zoos have more than 24 tigers. 9 zoos. And we're done.

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