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Finding the Fourth Proportional to 781.85, 1,172.55 and 261.86

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Solution

The fourth proportional to 781.85, 1,172.55 and 261.86 is: 392.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.85 : 1,172.55 = 261.86 : x
  2. Step 2: Convert to fraction form
    781.85/1,172.55 = 261.86/x
  3. Step 3: Cross multiply
    781.85x = 1,172.55 × 261.86
  4. Step 4: Simplify right side
    781.85x = 307,038.08
  5. Step 5: Solve for x
    x = 307,038.08/781.85
  6. Step 6: Final answer
    x = 392.71

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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.