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Finding the Fourth Proportional to 781.88, 1,078.55 and 688.85

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Solution

The fourth proportional to 781.88, 1,078.55 and 688.85 is: 950.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.88 : 1,078.55 = 688.85 : x
  2. Step 2: Convert to fraction form
    781.88/1,078.55 = 688.85/x
  3. Step 3: Cross multiply
    781.88x = 1,078.55 × 688.85
  4. Step 4: Simplify right side
    781.88x = 742,956.93
  5. Step 5: Solve for x
    x = 742,956.93/781.88
  6. Step 6: Final answer
    x = 950.22

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.