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Math Problems
Grade 8
Estimate population size using proportions
For a research project on rodents,
41
41
41
chipmunks were tagged and released. Later, researchers counted
320
320
320
chipmunks in the area. Of the chipmunks they counted,
16
16
16
had tags. To the nearest whole number, what is the best estimate for the chipmunk population?
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Scientists captured, tagged, and released
47
47
47
ducks as part of a research study. A week later, the scientists returned to the area and found
23
23
23
tagged ducks out of the
230
230
230
ducks they counted. To the nearest whole number, what is the best estimate for the duck population?
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Navigate
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Window
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Help
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Acellus Learning
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Recording
2
2
2
-Digit Addition
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8
+
8
=
16
8+8=16
8
+
8
=
16
\newline
How many ones are in
16
16
16
?
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tens
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Enter
\newline
2003
2003
2003
-
2024
2024
2024
International Academy of Science. All Rights Reserved.
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The number of telephone lines in each country in Central America and the Caribbean is shown in a dot plot. The number of telephone lines in each country has been rounded to the nearest
250
250
250
thousand. According to the dot plot, what is the median number of telephone lines in thousands?
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The total cost of a new automobile priced at
$
26
,
372
\$26,372
$26
,
372
including sales tax is
$
28
,
482
\$28,482
$28
,
482
.
\newline
Find the sales tax to the nearest percent.
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Two surveyors estimate the height of a nearby hill. One stands
5
m
5\,\text{m}
5
m
away from the other on horizontal ground holding a measuring stick vertically. The other surveyor finds a ＂line of sight＂ to the top of the hill, and observes that this line passes the vertical stick at a height of
2.4
m
2.4\,\text{m}
2.4
m
. They measure the distance from the stick to the top of the hill to be
1500
m
1500\,\text{m}
1500
m
using laser equipment. Find, correct to the nearest metre, their estimate for the height of the hill.
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Priya spends at least
3.5
3.5
3.5
hours practicing her English each week. If she spends
7
7
7
days a week practicing, what best describes the average number of hours she practices each day?
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In
2019
2019
2019
, the population of the City of Detroit was approximately
670
670
670
thousand. The land area of the City of Detroit is approximately
138.7
138.7
138.7
square miles. Which of the following is closest to the population density of the City of Detroit in
2019
2019
2019
in people per square mile of land area?
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John volunteers on the weekend at the Central Library. As a school project, he decides to record how many people visit the library, and where they go. On Saturday,
468
468
468
people went to The Youth Wing,
324
324
324
people went to Social Issues, and
356
356
356
went to Fiction and Literature.
\newline
On Sunday, the library had
1100
1100
1100
total visitors. Based on what John had recorded on Saturday, about how many people should be expected to go to Social Issues? Round your answer to the nearest whole number.
\newline
Answer:
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In one town there are
25
25
25
drivers under the age of
21
21
21
. There are a total of
225
225
225
drivers in town. what is the fraction of drivers under
21
21
21
?
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An online furniture store sells chairs for
$
50
\$ 50
$50
each and tables for
$
250
\$ 250
$250
each. Every day, the store can ship no more than
32
32
32
pieces of furniture and must sell at least
$
3200
\$ 3200
$3200
worth of chairs and tables. If
9
9
9
tables were sold, determine all possible values for the number of chairs that the store must sell in order to meet the requirements.
\newline
Answer:
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The annual energy consumption of the town where Camilla lives increases at a rate that is proportional at any time to the energy consumption at that time.
\newline
The town consumed
4
4
4
.
4
4
4
trillion British thermal units (BTUs) initially, and it consumed
5
5
5
.
5
5
5
trillion BTUs annually after
5
5
5
years.
\newline
What is the town's annual energy consumption, in trillions of BTUs, after
9
9
9
years?
\newline
Choose
1
1
1
answer:
\newline
(A)
6
6
6
.
6
6
6
\newline
(B)
32
32
32
.
8
8
8
\newline
(C)
41
41
41
.
8
8
8
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