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Finding the Fourth Proportional to 390.87, 585.54 and 208.20

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Solution

The fourth proportional to 390.87, 585.54 and 208.20 is: 311.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.87 : 585.54 = 208.20 : x
  2. Step 2: Convert to fraction form
    390.87/585.54 = 208.20/x
  3. Step 3: Cross multiply
    390.87x = 585.54 × 208.20
  4. Step 4: Simplify right side
    390.87x = 121,909.43
  5. Step 5: Solve for x
    x = 121,909.43/390.87
  6. Step 6: Final answer
    x = 311.89

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.