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Finding the Fourth Proportional to 86.96, 129.71 and 77.85

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Solution

The fourth proportional to 86.96, 129.71 and 77.85 is: 116.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.96 : 129.71 = 77.85 : x
  2. Step 2: Convert to fraction form
    86.96/129.71 = 77.85/x
  3. Step 3: Cross multiply
    86.96x = 129.71 × 77.85
  4. Step 4: Simplify right side
    86.96x = 10,097.53
  5. Step 5: Solve for x
    x = 10,097.53/86.96
  6. Step 6: Final answer
    x = 116.12

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.