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Finding the Fourth Proportional to 636.40, 878.30 and 387.87

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Solution

The fourth proportional to 636.40, 878.30 and 387.87 is: 535.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    636.40 : 878.30 = 387.87 : x
  2. Step 2: Convert to fraction form
    636.40/878.30 = 387.87/x
  3. Step 3: Cross multiply
    636.40x = 878.30 × 387.87
  4. Step 4: Simplify right side
    636.40x = 340,666.22
  5. Step 5: Solve for x
    x = 340,666.22/636.40
  6. Step 6: Final answer
    x = 535.30

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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.