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Finding the Fourth Proportional to 645.78, 969.90 and 553.44

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Solution

The fourth proportional to 645.78, 969.90 and 553.44 is: 831.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.78 : 969.90 = 553.44 : x
  2. Step 2: Convert to fraction form
    645.78/969.90 = 553.44/x
  3. Step 3: Cross multiply
    645.78x = 969.90 × 553.44
  4. Step 4: Simplify right side
    645.78x = 536,781.46
  5. Step 5: Solve for x
    x = 536,781.46/645.78
  6. Step 6: Final answer
    x = 831.21

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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.