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Finding the Fourth Proportional to 86.72, 129.78 and 52.56

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Solution

The fourth proportional to 86.72, 129.78 and 52.56 is: 78.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.72 : 129.78 = 52.56 : x
  2. Step 2: Convert to fraction form
    86.72/129.78 = 52.56/x
  3. Step 3: Cross multiply
    86.72x = 129.78 × 52.56
  4. Step 4: Simplify right side
    86.72x = 6,821.24
  5. Step 5: Solve for x
    x = 6,821.24/86.72
  6. Step 6: Final answer
    x = 78.66

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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.