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Finding the Fourth Proportional to 86.05, 128.87 and 55.47

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Solution

The fourth proportional to 86.05, 128.87 and 55.47 is: 83.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.05 : 128.87 = 55.47 : x
  2. Step 2: Convert to fraction form
    86.05/128.87 = 55.47/x
  3. Step 3: Cross multiply
    86.05x = 128.87 × 55.47
  4. Step 4: Simplify right side
    86.05x = 7,148.42
  5. Step 5: Solve for x
    x = 7,148.42/86.05
  6. Step 6: Final answer
    x = 83.07

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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.