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Finding the Fourth Proportional to 86.56, 129.14 and 78.70

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Solution

The fourth proportional to 86.56, 129.14 and 78.70 is: 117.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.56 : 129.14 = 78.70 : x
  2. Step 2: Convert to fraction form
    86.56/129.14 = 78.70/x
  3. Step 3: Cross multiply
    86.56x = 129.14 × 78.70
  4. Step 4: Simplify right side
    86.56x = 10,163.32
  5. Step 5: Solve for x
    x = 10,163.32/86.56
  6. Step 6: Final answer
    x = 117.41

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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.