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Finding the Fourth Proportional to 390.87, 539.48 and 225.20

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Solution

The fourth proportional to 390.87, 539.48 and 225.20 is: 310.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.87 : 539.48 = 225.20 : x
  2. Step 2: Convert to fraction form
    390.87/539.48 = 225.20/x
  3. Step 3: Cross multiply
    390.87x = 539.48 × 225.20
  4. Step 4: Simplify right side
    390.87x = 121,490.90
  5. Step 5: Solve for x
    x = 121,490.90/390.87
  6. Step 6: Final answer
    x = 310.82

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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.