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Finding the Fourth Proportional to 86.69, 129.41 and 77.58

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Solution

The fourth proportional to 86.69, 129.41 and 77.58 is: 115.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.69 : 129.41 = 77.58 : x
  2. Step 2: Convert to fraction form
    86.69/129.41 = 77.58/x
  3. Step 3: Cross multiply
    86.69x = 129.41 × 77.58
  4. Step 4: Simplify right side
    86.69x = 10,039.53
  5. Step 5: Solve for x
    x = 10,039.53/86.69
  6. Step 6: Final answer
    x = 115.81

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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.