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Finding the Fourth Proportional to 641.39, 885.20 and 405.45

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Solution

The fourth proportional to 641.39, 885.20 and 405.45 is: 559.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.39 : 885.20 = 405.45 : x
  2. Step 2: Convert to fraction form
    641.39/885.20 = 405.45/x
  3. Step 3: Cross multiply
    641.39x = 885.20 × 405.45
  4. Step 4: Simplify right side
    641.39x = 358,902.31
  5. Step 5: Solve for x
    x = 358,902.31/641.39
  6. Step 6: Final answer
    x = 559.57

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.