Transcript Chapter 4 Powerpoint

Mathematics: Applications and Concepts, Course 1 Interactive Chalkboard
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Example 1 Multiply Decimals
Example 2 Multiply Decimals
Example 3 Annex Zeros in the Product
Example 4 Annex Zeros in the Product
Example 5 Scientific Notation
.
Method 1 Use estimation.
Round 18.9 to 19.
33
Since the estimate is 76, place
the decimal point after the 5.
Method 2 Count decimal places.
33
There is one place to the right of the decimal point.
Count the same number of
decimal places from right to left.
Answer: 75.6
Find
Answer: 100.8
Find
Method 1 Use estimation.
Round 0.56 to 0.5.
4
Since the estimate is 3.5,
place the decimal point after
the 3.
Method 2 Count decimal places.
4
There are two places to the
right of the decimal point.
Count the same number of
decimal places from right to left.
Answer: 3.92
Find
Answer: 3.32
Find
Estimate
The product is close
to zero.
1
There are three decimal places.
Annex a zero on the left of 48 to
make three decimal places.
Check
Answer: 0.048
Find
Answer: 0.092
ALGEBRA Evaluate
Replace g with 0.0091.
There are four decimal places.
Annex a zero to make four decimal places.
Answer: 0.0455
ALGEBRA Evaluate
Answer: 0.0186
ASTRONOMY The average distance from Earth to the
Sun is
kilometers. Write this distance in
standard form.
Method 1 Use order of operations.
Evaluate
first. Then multiply.
Method 2 Use mental math.
Move the decimal point 8 places.
Answer: So, the average distance is 150,000,000
kilometers.
ARCHAEOLOGY An archaeologist claims that a
particular artifact is
years old. Write this age
in standard form.
Answer: 240,000 years
Example 1 Multiply Decimals
Example 2 Multiply Decimals
Example 3 Evaluate an Expression
Example 4 Multiply Decimals to Solve a Problem
Find
Estimate
one decimal place
one decimal place
two decimal places
Answer: The product is 24.07. Compared to the estimate,
the product is reasonable.
Find
Answer: 8.74
Find
Estimate
one decimal place
two decimal places
three decimal places
Answer: The product is 0.636. Compared to the estimate,
the product is reasonable.
Find
Answer: 0.899
ALGEBRA Evaluate
Replace r with 0.92.
two decimal places
one decimal place
three decimal places
Answer: 6.256
ALGEBRA Evaluate
Answer: 0.1334
MONEY Carmen earns $4.60 an hour working part-time
as a painter’s assistant. She worked a total of 15.75
hours one week. How much money did she earn?
Estimate
two decimal places
two decimal places
The product has four decimal
places. You can drop the two zeros
at the end because
Answer: Carmen earned $72.45.
MONEY Susan earns $5.80 an hour working at a local
video store. She worked a total of 28.25 hours one
week. How much money did she earn?
Answer: $163.85
Example 1 Divide a Decimal by a 1-Digit Number
Example 2 Divide a Decimal by a 2-Digit Number
Example 3 Round a Quotient
Find
Estimate
Place the decimal point directly above
the decimal point in the dividend.
Divide as with whole numbers.
Answer: The quotient is 15.3. Compared to the
estimate, the quotient is reasonable.
Find
Answer: 12.7
Find
Place the decimal point.
Annex a zero and continue dividing.
Answer: The quotient is 0.395. Compared to the
estimate, the quotient is reasonable.
Find
Answer: 0.36
GRID-IN TEST ITEM During a science experiment,
Nita measured the mass of four unknown samples.
Her data table is shown below. What is the mean
mass of the four samples?
Sample 1
6.23 g
Sample 2
5.81 g
Sample 3
5.93 g
Sample 4
6.47 g
Read the Test Item
To find the mean mass, add the four masses and then
divide the sum by four.
Solve the Test Item
Place the decimal point.
Divide as with whole numbers.
The mean mass is 6.11 grams.
Answer:
GRID-IN TEST ITEM The birth weights of four babies
born at City Hospital last Friday are given in pounds.
What is the mean birth weight?
Baby 1
7.35 lb
Baby 2
6.52 lb
Baby 3
8.33 lb
Baby 4
7.68 lb
Answer:
Example 1 Divide by Decimals
Example 2 Zeros in the Quotient and Dividend
Example 3 Zeros in the Quotient and Dividend
Example 4 Round Quotients
Find
Estimate
Multiply by 10 to make
whole numbers.
Place the decimal point.
Divide as with whole
numbers.
Multiply by the
same number, 10.
Annex a zero to continue.
Check
Answer: 59.4 divided by 3.6 is 16.5. Compare to the
estimate.
Find
Answer: 13.5
Find
Place the decimal point.
Divide.
Multiply each
by 1,000.
Check
Answer:
Write a zero in the ones
place of the quotient
because
Find
Answer: 130
Find
Place the decimal point.
Multiply each
by 10.
Check
Answer:
13 does not go into 5, so
write a 0 in the tenths place.
Find
Answer: 0.06
STOCK Leon bought a stock at $42.88 per share. If he
spent $786.85, how many shares did he buy? Round to
the nearest tenth.
Multiply the divisor and the dividend by 100.
Answer: To the nearest tenth,
So, Leon was able to buy about 18.4 shares.
STOCK Kyle bought a stock at $23.55 per share. If he
spent $771.28, how many shares did he buy? Round to
the nearest tenth.
Answer: 32.8
Example 1 Find the Perimeter
Example 2 Find the Perimeter of a Square
Find the perimeter of the rectangle.
Write the formula.
Replace with 7 and w with 4.
Multiply.
Add.
Answer: The perimeter is 22 meters.
Find the perimeter of a rectangle.
Answer: 40.2 in.
ARCHITECTURE The base of the Eiffel Tower is
shaped like a square with 125-meter sides. What is the
perimeter of the base?
Words
Perimeter of a square is equal to four
times the measure of any side.
Symbols
Equation
Write the equation.
Multiply.
Answer: The perimeter of the base of the Eiffel
Tower is 500 meters.
ARCHITECTURE A new discount store is being built
with its base in the shape of a square with 75-foot
sides. What is the perimeter of the base?
Answer: 300 ft
Example 1 Find the Circumference of a Circle
Example 2 Use Circumference to Solve a Problem
Find the circumference of a circle whose diameter is
6.8 centimeters. Round to the nearest tenth.
You know the diameter. Use
Write the formula.
Replace with 3.14
and d with 6.8.
Multiply.
Answer: The circumference is about 21.4 centimeters.
Find the circumference of a circle whose diameter is
12.4 inches. Round to the nearest tenth.
Answer: about 38.9 in.
ARCHAEOLOGY In the Chinese city of Xi’an,
thousands of terra cotta soldiers were discovered
during an archaeological excavation. The distance
from the center of the ancient city to its surrounding
circular walls is about 1.89 kilometers. What is the
circumference of the wall?
You know the radius of the circle.
Write the formula.
Multiply.
Answer: To the nearest tenth, the circumference is about
11.9 kilometers.
SWIMMING POOL A new swimming pool is being built
for young children at the community recreation center.
The pool is circular and the distance from the center
fountain to the edges is 8.5 feet. What is the
circumference of the pool?
Answer: about 53.4 ft