6-1a-Ratio-proportion- Grade 9 25-26.ppt

Math

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6.1 Ratios &
Proportion

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A RATIO is a quotient
that compare 2 quantities.
3
4
3 to 43 : 4
These are all the same.

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A Proportion is an equation
of two equal ratios.

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Proportion is true if Proportion is true if
fractions fractions are are equalequal when when in in
lowest terms. lowest terms.
3 3 44 5 5
6 8 106 8 10
==
allall
reducereduce
to 1/2to 1/2

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the Extremes.Extremes.
the Means.Means.

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The product of the meansproduct of the means
equals the product of the product of the
extremesextremes..
Cross products are equal.
2 • 12 = 3 • 8
24 = 24

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To Solve Proportions
Find n
9 n =(3) (6)
9 n = 18
n = 2

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7
44
=
w
5000 - w5000 - w
7 ( 5000 - w) = 4 w
35,000 = 11 w
3182 = w
35000 - 7 w = 4 w

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3: 8 = n : 6
3 = n
8 6
18 = 8 n
18/8 = n
2.25 = n

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Similar FiguresSimilar Figures
A BA B
C DC D
E FE F
G HG H
Corresponding <s =Corresponding <s =
Sides are proportionalSides are proportional

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A BA B
C DC D
E FE F
G HG H
ABCD ~ EFGHABCD ~ EFGH
1010
1212
1313
Find GHFind GHsmall small 1010
big 13big 13
==
1212
GHGH

12. fguilbert
small small 1010
big 13big 13
==
1212
GHGH
1010 GH = (12)(13)GH = (12)(13)
10 GH = 15610 GH = 156
GH = 15.6GH = 15.6
mathbyart.com

13. fguilbert
A BA B
C DC D
E FE F
G HG H
ABCD ~ EFGHABCD ~ EFGH
110110
Find Find mm<E<E
<<A = A = <E<E mm<<E = 110E = 110
00~
110

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A
B C
D
E F
AB C ~ DEF
8 6
5
Find EF

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A
B C
D
E F
AB C ~ DEF
8 6
5
small
big
6
8
=
EF
5

16. fguilbert
6
8
=
EF
5
x
(6)(5) = 8x
30 = 8x
30/8 = x
3.75 = x
mathbyart.com

17. fguilbert
The desire to succeed The desire to succeed
means nothing means nothing
without the without the
will to will to
prepare!prepare!
thought for the daythought for the day