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Finding the Fourth Proportional to 109.85, 164.87 and 85.42

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Solution

The fourth proportional to 109.85, 164.87 and 85.42 is: 128.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.85 : 164.87 = 85.42 : x
  2. Step 2: Convert to fraction form
    109.85/164.87 = 85.42/x
  3. Step 3: Cross multiply
    109.85x = 164.87 × 85.42
  4. Step 4: Simplify right side
    109.85x = 14,081.94
  5. Step 5: Solve for x
    x = 14,081.94/109.85
  6. Step 6: Final answer
    x = 128.19

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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.