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Finding the Fourth Proportional to 390.78, 539.42 and 259.83

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Solution

The fourth proportional to 390.78, 539.42 and 259.83 is: 358.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.78 : 539.42 = 259.83 : x
  2. Step 2: Convert to fraction form
    390.78/539.42 = 259.83/x
  3. Step 3: Cross multiply
    390.78x = 539.42 × 259.83
  4. Step 4: Simplify right side
    390.78x = 140,156.20
  5. Step 5: Solve for x
    x = 140,156.20/390.78
  6. Step 6: Final answer
    x = 358.66

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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.