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Finding the Fourth Proportional to 636.90, 878.90 and 400.80

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Solution

The fourth proportional to 636.90, 878.90 and 400.80 is: 553.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    636.90 : 878.90 = 400.80 : x
  2. Step 2: Convert to fraction form
    636.90/878.90 = 400.80/x
  3. Step 3: Cross multiply
    636.90x = 878.90 × 400.80
  4. Step 4: Simplify right side
    636.90x = 352,263.12
  5. Step 5: Solve for x
    x = 352,263.12/636.90
  6. Step 6: Final answer
    x = 553.09

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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.