Transcript Scientific Calculations - Sikeston R-6

Teacher Page
• Scientific Inquiry A. Processes of Scientific
Inquiry.
• State standards 1.8, 4.1
• 7th grade assessment
• Students should be able to find the mean and
median of sets of data, calculate percent and
ratios, and determine the units in which the values
should be expressed.
• View lesson before using with students to see what
materials are needed and to learn mouse click
commands.
Sometimes after you make measurements, you
have to analyze your data to see what it means.
This might involve doing calculations with
your data. P e a n u t L e n g th (m m )
• Find an Average
• The table shows the
lengths of a group of
unshelled peanuts.
• What is the average
length of the peanuts?
• You can use a calculator
to help you find out.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
32
29
30
31
33
26
28
27
29
29
32
31
23
36
31
Find the Average
• Look at the list of lengths,
and estimate what you think
the average length is.
• Add the numbers.
• Find the average length of
the peanuts by dividing your
total by the number of
peanuts measured.
• How close was your
estimate to the actual
average?
Peanut
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
L e n g th (m m )
32
29
30
31
33
26
28
27
29
29
32
31
23
36
31
There are three kinds of
averages--
• Mean
• Median
• Mode
• Does it matter which one
you use?
Find the Mean
• The mean is what most
people think of when they
hear the word average.
• Add the numbers.
• Find the mean by dividing
your total by the number of
weeks.
• Rounded up to one decimal
point, your mean should be
2.7.
Week
1
2
3
4
5
6
7
8
9
10
11
Rain (cm)
2.0
1.4
0.0
0.5
1.2
2.5
1.8
1.4
2.4
8.6
7.5
Find the Median
• The median is the
middle number
when the numbers
are arranged in
order of size.
• Arrange the rainfall
measurements in
order of size.
Week
1
2
3
4
5
6
7
8
9
10
11
Rain (cm)
2.0
1.4
0.0
0.5
1.2
2.5
1.8
1.4
2.4
8.6
7.5
Find the Median
• The median is
1.8. This number
is in the middle;
there are five
numbers above it
and five numbers
below it.
0.0
0.5
1.2
1.4
1.4
1.8
2.0
2.4
2.5
7.5
8.6
Find the Mode
• The mode is the
number that occurs
most frequently.
• From the ranked set
of data, you can see
that the most
frequent number is
1.4.
• It occurs twice.
0.0
0.5
1.2
1.4
1.4
1.8
2.0
2.4
2.5
7.5
8.6
Find the Mean, Median and
Mode
Peanut
• The table shows the
length of 15 peanuts.
• Find the mean, median,
and mode for this set of
data.
• Which do you think best
represents a typical
peanut?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
L e n g th (m m )
32
29
30
31
33
26
28
27
29
29
32
31
23
36
31
Find the Percent
• Sometimes numbers
are given as percents
(%).
• Percent literally means
“per hundred.”
• For example, 28%
means 28 out of 100.
•What if there are
about 14,000 trees in
the forest and 28%
are over 50 years
old?
•How many of them
are over 50 years
old?
14000 X 28%
The answer should be 3,920.