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Finding the Fourth Proportional to 390.20, 585.58 and 287.76

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Solution

The fourth proportional to 390.20, 585.58 and 287.76 is: 431.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.20 : 585.58 = 287.76 : x
  2. Step 2: Convert to fraction form
    390.20/585.58 = 287.76/x
  3. Step 3: Cross multiply
    390.20x = 585.58 × 287.76
  4. Step 4: Simplify right side
    390.20x = 168,506.50
  5. Step 5: Solve for x
    x = 168,506.50/390.20
  6. Step 6: Final answer
    x = 431.85

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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.