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Finding the Fourth Proportional to 720.76, 1,081.56 and 287.86

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Solution

The fourth proportional to 720.76, 1,081.56 and 287.86 is: 431.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.76 : 1,081.56 = 287.86 : x
  2. Step 2: Convert to fraction form
    720.76/1,081.56 = 287.86/x
  3. Step 3: Cross multiply
    720.76x = 1,081.56 × 287.86
  4. Step 4: Simplify right side
    720.76x = 311,337.86
  5. Step 5: Solve for x
    x = 311,337.86/720.76
  6. Step 6: Final answer
    x = 431.96

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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.