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Finding the Fourth Proportional to 76.78, 115.25 and 56.43

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Solution

The fourth proportional to 76.78, 115.25 and 56.43 is: 84.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.78 : 115.25 = 56.43 : x
  2. Step 2: Convert to fraction form
    76.78/115.25 = 56.43/x
  3. Step 3: Cross multiply
    76.78x = 115.25 × 56.43
  4. Step 4: Simplify right side
    76.78x = 6,503.56
  5. Step 5: Solve for x
    x = 6,503.56/76.78
  6. Step 6: Final answer
    x = 84.70

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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.