Ratios and Proportions.notebook
October 21, 2014
Solving Problems with Ratios and Proportions
RHS has 350 freshmen. There are about 150 girls. What is the ratio of girls to boys?
Ratio: the result of dividing one number or expression by another. Yes, basically a fraction.
*A ratio may be written as3:4, 3
Let's do the reverse:
to 4, or
¾.
move white space
Say all the information you are given is that there is a 3 : 4 ratio of girls to boys and that there is a total of 350 boys and girls. How would you figure out how many of each there are?
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Ratios and Proportions.notebook
October 21, 2014
Solving Problems with Ratios and Proportions
1. Excellent Environmental estimates that a pond contains 3000 fish. Some are catfish,
perch, and the rest are bass. After testing samples by dragging a net through the pond,
they determine that the ratio of catfish to perch to bass is 2:5:3.
Scale Factor 1
2
3
4
300
x
Catfish Perch Bass Total Fish A. Represent each type of fish using x.
Catfish:
Perch:
Bass:
B. Write an equation showing the total number of fish in the pond.
C. Find the number of each type of fish in the pond.
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Ratios and Proportions.notebook
October 21, 2014
Solving Problems with Ratios and Proportions
2. Mae Berry has eighteen grandchildren on her son's side and twelve grandchildren
on her daughter's side. If Mae Berry uses the ratio of grandchildren to divide up
7200 acres of land, how much land will the son's children receive, and how much
will the daughter's children receive?
3. The sides of a triangle have lengths in the ratio 3:5:7. The perimeter of the
triangle is ninety centimeters. Find the lengths of the sides.
4. The ratio of two integers is 9:7. Their sum is 1024. Find the two integers.
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Ratios and Proportions.notebook
October 21, 2014
Proportion: a statement where two ratios are equal.
*When two ratios are equal, the cross products of the ratios are equal.
5. The ratio of two integers is ¾. The smaller integer is 54. Find the larger.
6. A 20 ft. tall pole casts a shadow of 12 feet. At the same time of the day, how
tall of a shadow would a 5 ft. tall pole cast?
7. ΔABC is similar to ΔDEF, what is the length of DE ?
A
D
9
B
15
12
C
E
8
F
4