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Finding the Fourth Proportional to 1,209.93, 1,815 and 429.85

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Solution

The fourth proportional to 1,209.93, 1,815 and 429.85 is: 644.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.93 : 1,815 = 429.85 : x
  2. Step 2: Convert to fraction form
    1,209.93/1,815 = 429.85/x
  3. Step 3: Cross multiply
    1,209.93x = 1,815 × 429.85
  4. Step 4: Simplify right side
    1,209.93x = 780,177.75
  5. Step 5: Solve for x
    x = 780,177.75/1,209.93
  6. Step 6: Final answer
    x = 644.81

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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.