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Finding the Fourth Proportional to 86.65, 129.98 and 73.78

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Solution

The fourth proportional to 86.65, 129.98 and 73.78 is: 110.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.65 : 129.98 = 73.78 : x
  2. Step 2: Convert to fraction form
    86.65/129.98 = 73.78/x
  3. Step 3: Cross multiply
    86.65x = 129.98 × 73.78
  4. Step 4: Simplify right side
    86.65x = 9,589.92
  5. Step 5: Solve for x
    x = 9,589.92/86.65
  6. Step 6: Final answer
    x = 110.67

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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.