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Finding the Fourth Proportional to 86.76, 129.54 and 72.96

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Solution

The fourth proportional to 86.76, 129.54 and 72.96 is: 108.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.76 : 129.54 = 72.96 : x
  2. Step 2: Convert to fraction form
    86.76/129.54 = 72.96/x
  3. Step 3: Cross multiply
    86.76x = 129.54 × 72.96
  4. Step 4: Simplify right side
    86.76x = 9,451.24
  5. Step 5: Solve for x
    x = 9,451.24/86.76
  6. Step 6: Final answer
    x = 108.94

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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.