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Finding the Fourth Proportional to 208.85, 313.31 and 87.12

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Solution

The fourth proportional to 208.85, 313.31 and 87.12 is: 130.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.85 : 313.31 = 87.12 : x
  2. Step 2: Convert to fraction form
    208.85/313.31 = 87.12/x
  3. Step 3: Cross multiply
    208.85x = 313.31 × 87.12
  4. Step 4: Simplify right side
    208.85x = 27,295.79
  5. Step 5: Solve for x
    x = 27,295.79/208.85
  6. Step 6: Final answer
    x = 130.70

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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.