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Finding the Fourth Proportional to 86.68, 129.90 and 76.76

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Solution

The fourth proportional to 86.68, 129.90 and 76.76 is: 115.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.68 : 129.90 = 76.76 : x
  2. Step 2: Convert to fraction form
    86.68/129.90 = 76.76/x
  3. Step 3: Cross multiply
    86.68x = 129.90 × 76.76
  4. Step 4: Simplify right side
    86.68x = 9,971.12
  5. Step 5: Solve for x
    x = 9,971.12/86.68
  6. Step 6: Final answer
    x = 115.03

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.