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Finding the Fourth Proportional to 112.78, 169.08 and 85.69

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Solution

The fourth proportional to 112.78, 169.08 and 85.69 is: 128.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    112.78 : 169.08 = 85.69 : x
  2. Step 2: Convert to fraction form
    112.78/169.08 = 85.69/x
  3. Step 3: Cross multiply
    112.78x = 169.08 × 85.69
  4. Step 4: Simplify right side
    112.78x = 14,488.47
  5. Step 5: Solve for x
    x = 14,488.47/112.78
  6. Step 6: Final answer
    x = 128.47

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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.