Ratios Proportions 4D2373
1. **Problem 1:** Find the ratio of red cars to blue cars given the ratios red:green = 5:6 and green:blue = 3:10.
Step 1: Write the given ratios:
- Red : Green = 5 : 6
- Green : Blue = 3 : 10
Step 2: To find Red : Blue, we need to express the ratios with the same green term.
Step 3: Find the least common multiple (LCM) of the green parts 6 and 3, which is 6.
Step 4: Adjust the ratios:
- Red : Green = 5 : 6 (already with green = 6)
- Green : Blue = 3 : 10 → multiply both terms by 2 to get 6 : 20
Step 5: Now, Red : Green : Blue = 5 : 6 : 20
Step 6: Therefore, Red : Blue = 5 : 20 = 1 : 4
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2. **Problem 2:** When $a$ is multiplied by 1.75 it becomes $b$. Express $a:b$ in simplest form.
Step 1: Given $b = 1.75a$
Step 2: The ratio $a:b = a : 1.75a$
Step 3: Divide both terms by $a$ (assuming $a \neq 0$):
$$a:b = 1 : 1.75$$
Step 4: Convert 1.75 to fraction: $1.75 = \frac{7}{4}$
Step 5: So,
$$a:b = 1 : \frac{7}{4} = \frac{4}{4} : \frac{7}{4} = 4 : 7$$
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3. **Problem 3:** $540$ is divided among three brothers in the ratio $\frac{3}{4} : \frac{2}{3} : \frac{5}{6}$. Find the amount each receives.
Step 1: Write the ratio terms:
$$\frac{3}{4}, \frac{2}{3}, \frac{5}{6}$$
Step 2: Find the least common denominator (LCD) of 4, 3, and 6, which is 12.
Step 3: Convert each ratio term to have denominator 12:
$$\frac{3}{4} = \frac{9}{12}, \quad \frac{2}{3} = \frac{8}{12}, \quad \frac{5}{6} = \frac{10}{12}$$
Step 4: The ratio is now $9 : 8 : 10$
Step 5: Sum of ratio parts:
$$9 + 8 + 10 = 27$$
Step 6: Each part value:
$$\frac{540}{27} = 20$$
Step 7: Amounts received:
- Brother 1: $9 \times 20 = 180$
- Brother 2: $8 \times 20 = 160$
- Brother 3: $10 \times 20 = 200$
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4. **Problem 4:** A man left a legacy of 9450 to be divided among four daughters in the ratio 6:7:8:9. Find the amount each daughter receives.
Step 1: Sum of ratio parts:
$$6 + 7 + 8 + 9 = 30$$
Step 2: Each part value:
$$\frac{9450}{30} = 315$$
Step 3: Amounts received:
- Daughter 1: $6 \times 315 = 1890$
- Daughter 2: $7 \times 315 = 2205$
- Daughter 3: $8 \times 315 = 2520$
- Daughter 4: $9 \times 315 = 2835$