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Finding the Fourth Proportional to 390.87, 539.87 and 279.09

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Solution

The fourth proportional to 390.87, 539.87 and 279.09 is: 385.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.87 : 539.87 = 279.09 : x
  2. Step 2: Convert to fraction form
    390.87/539.87 = 279.09/x
  3. Step 3: Cross multiply
    390.87x = 539.87 × 279.09
  4. Step 4: Simplify right side
    390.87x = 150,670.92
  5. Step 5: Solve for x
    x = 150,670.92/390.87
  6. Step 6: Final answer
    x = 385.48

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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.