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Finding the Fourth Proportional to 78.69, 107.85 and 78.55

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Solution

The fourth proportional to 78.69, 107.85 and 78.55 is: 107.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.69 : 107.85 = 78.55 : x
  2. Step 2: Convert to fraction form
    78.69/107.85 = 78.55/x
  3. Step 3: Cross multiply
    78.69x = 107.85 × 78.55
  4. Step 4: Simplify right side
    78.69x = 8,471.81
  5. Step 5: Solve for x
    x = 8,471.81/78.69
  6. Step 6: Final answer
    x = 107.66

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.