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Finding the Fourth Proportional to 981.47, 1,469.78 and 720.86

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Solution

The fourth proportional to 981.47, 1,469.78 and 720.86 is: 1,079.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.47 : 1,469.78 = 720.86 : x
  2. Step 2: Convert to fraction form
    981.47/1,469.78 = 720.86/x
  3. Step 3: Cross multiply
    981.47x = 1,469.78 × 720.86
  4. Step 4: Simplify right side
    981.47x = 1,059,497.36
  5. Step 5: Solve for x
    x = 1,059,497.36/981.47
  6. Step 6: Final answer
    x = 1,079.50

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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.