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Finding the Fourth Proportional to 77.80, 106.81 and 66.86

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Solution

The fourth proportional to 77.80, 106.81 and 66.86 is: 91.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.80 : 106.81 = 66.86 : x
  2. Step 2: Convert to fraction form
    77.80/106.81 = 66.86/x
  3. Step 3: Cross multiply
    77.80x = 106.81 × 66.86
  4. Step 4: Simplify right side
    77.80x = 7,141.32
  5. Step 5: Solve for x
    x = 7,141.32/77.80
  6. Step 6: Final answer
    x = 91.79

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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.