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Finding the Fourth Proportional to 86.06, 128.90 and 42.66

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Solution

The fourth proportional to 86.06, 128.90 and 42.66 is: 63.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.06 : 128.90 = 42.66 : x
  2. Step 2: Convert to fraction form
    86.06/128.90 = 42.66/x
  3. Step 3: Cross multiply
    86.06x = 128.90 × 42.66
  4. Step 4: Simplify right side
    86.06x = 5,498.87
  5. Step 5: Solve for x
    x = 5,498.87/86.06
  6. Step 6: Final answer
    x = 63.90

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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.