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Big Ideas Math: Modeling Real Life, Grade 7

BI

Big Ideas Math: Modeling Real Life, Grade 7 View details

3. Identifying Proportional Relationships

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Exercise 20 Page 200

You can use cross products to determine if the ratios are equivalent.

No.

Practice makes perfect

To determine if the given ratios form a proportion. Let's first write them as fractions. ccc Ratio & & Fraction [0.8em] 24: 30 & → & 24/30 [1em] 3: 7/2 & → & 3/.7 /2. Then, we will set them equal to one another and use the Cross Products Property. If the resulting equation is true, then the ratios form a proportion.

24/30? =3/.7 /2.

Cross multiply

24*7/2 ? =30*3

Multiply

24*7/2 ? = 90

MoveLeftFacToNum

a*b/c= a* b/c

168/2? = 90

Calculate quotient

84 ≠ 90 *

No, the ratios do not form a proportion because the cross products are not equal.

Subchapter links

Try It p.196-198

Self-Assessment for Concept & Skills p.198

Self-Assessment for Problem Solving p.199

Review & Refresh p.200

Concept, Skills, & Problem Solving p.200-202