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Finding the Fourth Proportional to 86.00, 128.81 and 85.07

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Solution

The fourth proportional to 86.00, 128.81 and 85.07 is: 127.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.00 : 128.81 = 85.07 : x
  2. Step 2: Convert to fraction form
    86.00/128.81 = 85.07/x
  3. Step 3: Cross multiply
    86.00x = 128.81 × 85.07
  4. Step 4: Simplify right side
    86.00x = 10,958.40
  5. Step 5: Solve for x
    x = 10,958.40/86.00
  6. Step 6: Final answer
    x = 127.43

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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.