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Finding the Fourth Proportional to 86.13, 128.39 and 83.70

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Solution

The fourth proportional to 86.13, 128.39 and 83.70 is: 124.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.13 : 128.39 = 83.70 : x
  2. Step 2: Convert to fraction form
    86.13/128.39 = 83.70/x
  3. Step 3: Cross multiply
    86.13x = 128.39 × 83.70
  4. Step 4: Simplify right side
    86.13x = 10,745.82
  5. Step 5: Solve for x
    x = 10,745.82/86.13
  6. Step 6: Final answer
    x = 124.76

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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.