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Finding the Fourth Proportional to 77.76, 106.38 and 77.31

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Solution

The fourth proportional to 77.76, 106.38 and 77.31 is: 105.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.76 : 106.38 = 77.31 : x
  2. Step 2: Convert to fraction form
    77.76/106.38 = 77.31/x
  3. Step 3: Cross multiply
    77.76x = 106.38 × 77.31
  4. Step 4: Simplify right side
    77.76x = 8,224.24
  5. Step 5: Solve for x
    x = 8,224.24/77.76
  6. Step 6: Final answer
    x = 105.76

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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.