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Finding the Fourth Proportional to 86.87, 129.74 and 74.72

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Solution

The fourth proportional to 86.87, 129.74 and 74.72 is: 111.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.87 : 129.74 = 74.72 : x
  2. Step 2: Convert to fraction form
    86.87/129.74 = 74.72/x
  3. Step 3: Cross multiply
    86.87x = 129.74 × 74.72
  4. Step 4: Simplify right side
    86.87x = 9,694.12
  5. Step 5: Solve for x
    x = 9,694.12/86.87
  6. Step 6: Final answer
    x = 111.59

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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.