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Finding the Fourth Proportional to 86.88, 129.64 and 80.68

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Solution

The fourth proportional to 86.88, 129.64 and 80.68 is: 120.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.88 : 129.64 = 80.68 : x
  2. Step 2: Convert to fraction form
    86.88/129.64 = 80.68/x
  3. Step 3: Cross multiply
    86.88x = 129.64 × 80.68
  4. Step 4: Simplify right side
    86.88x = 10,459.36
  5. Step 5: Solve for x
    x = 10,459.36/86.88
  6. Step 6: Final answer
    x = 120.39

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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.