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Finding the Fourth Proportional to 122.61, 168.91 and 85.70

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Solution

The fourth proportional to 122.61, 168.91 and 85.70 is: 118.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    122.61 : 168.91 = 85.70 : x
  2. Step 2: Convert to fraction form
    122.61/168.91 = 85.70/x
  3. Step 3: Cross multiply
    122.61x = 168.91 × 85.70
  4. Step 4: Simplify right side
    122.61x = 14,475.59
  5. Step 5: Solve for x
    x = 14,475.59/122.61
  6. Step 6: Final answer
    x = 118.06

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.