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Finding the Fourth Proportional to 721.07, 1,081.76 and 428.46

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Solution

The fourth proportional to 721.07, 1,081.76 and 428.46 is: 642.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.07 : 1,081.76 = 428.46 : x
  2. Step 2: Convert to fraction form
    721.07/1,081.76 = 428.46/x
  3. Step 3: Cross multiply
    721.07x = 1,081.76 × 428.46
  4. Step 4: Simplify right side
    721.07x = 463,484.69
  5. Step 5: Solve for x
    x = 463,484.69/721.07
  6. Step 6: Final answer
    x = 642.77

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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.