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Finding the Fourth Proportional to 78.66, 109.26 and 77.90

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Solution

The fourth proportional to 78.66, 109.26 and 77.90 is: 108.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.66 : 109.26 = 77.90 : x
  2. Step 2: Convert to fraction form
    78.66/109.26 = 77.90/x
  3. Step 3: Cross multiply
    78.66x = 109.26 × 77.90
  4. Step 4: Simplify right side
    78.66x = 8,511.35
  5. Step 5: Solve for x
    x = 8,511.35/78.66
  6. Step 6: Final answer
    x = 108.20

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.