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Finding the Fourth Proportional to 112.50, 168.75 and 85.86

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Solution

The fourth proportional to 112.50, 168.75 and 85.86 is: 128.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    112.50 : 168.75 = 85.86 : x
  2. Step 2: Convert to fraction form
    112.50/168.75 = 85.86/x
  3. Step 3: Cross multiply
    112.50x = 168.75 × 85.86
  4. Step 4: Simplify right side
    112.50x = 14,488.88
  5. Step 5: Solve for x
    x = 14,488.88/112.50
  6. Step 6: Final answer
    x = 128.79

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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.