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Finding the Fourth Proportional to 813.90, 1,221.03 and 429.06

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Solution

The fourth proportional to 813.90, 1,221.03 and 429.06 is: 643.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.90 : 1,221.03 = 429.06 : x
  2. Step 2: Convert to fraction form
    813.90/1,221.03 = 429.06/x
  3. Step 3: Cross multiply
    813.90x = 1,221.03 × 429.06
  4. Step 4: Simplify right side
    813.90x = 523,895.13
  5. Step 5: Solve for x
    x = 523,895.13/813.90
  6. Step 6: Final answer
    x = 643.68

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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.