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Finding the Fourth Proportional to 208.57, 312.70 and 86.67

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Solution

The fourth proportional to 208.57, 312.70 and 86.67 is: 129.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.57 : 312.70 = 86.67 : x
  2. Step 2: Convert to fraction form
    208.57/312.70 = 86.67/x
  3. Step 3: Cross multiply
    208.57x = 312.70 × 86.67
  4. Step 4: Simplify right side
    208.57x = 27,100.15
  5. Step 5: Solve for x
    x = 27,100.15/208.57
  6. Step 6: Final answer
    x = 129.93

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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.