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Finding the Fourth Proportional to 1,209.12, 1,812.61 and 429

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Solution

The fourth proportional to 1,209.12, 1,812.61 and 429 is: 643.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.12 : 1,812.61 = 429 : x
  2. Step 2: Convert to fraction form
    1,209.12/1,812.61 = 429/x
  3. Step 3: Cross multiply
    1,209.12x = 1,812.61 × 429
  4. Step 4: Simplify right side
    1,209.12x = 777,609.69
  5. Step 5: Solve for x
    x = 777,609.69/1,209.12
  6. Step 6: Final answer
    x = 643.12

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Double scale
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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.