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Finding the Fourth Proportional to 86, 128.88 and 84.56

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Solution

The fourth proportional to 86, 128.88 and 84.56 is: 126.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    86 : 128.88 = 84.56 : x
  2. Step 2: Convert to fraction form
    86/128.88 = 84.56/x
  3. Step 3: Cross multiply
    86x = 128.88 × 84.56
  4. Step 4: Simplify right side
    86x = 10,898.09
  5. Step 5: Solve for x
    x = 10,898.09/86
  6. Step 6: Final answer
    x = 126.72

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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.