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Finding the Fourth Proportional to 207.50, 311.39 and 85.76

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Solution

The fourth proportional to 207.50, 311.39 and 85.76 is: 128.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.50 : 311.39 = 85.76 : x
  2. Step 2: Convert to fraction form
    207.50/311.39 = 85.76/x
  3. Step 3: Cross multiply
    207.50x = 311.39 × 85.76
  4. Step 4: Simplify right side
    207.50x = 26,704.59
  5. Step 5: Solve for x
    x = 26,704.59/207.50
  6. Step 6: Final answer
    x = 128.70

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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.