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Finding the Fourth Proportional to 208.21, 312.08 and 139.71

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Solution

The fourth proportional to 208.21, 312.08 and 139.71 is: 209.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.21 : 312.08 = 139.71 : x
  2. Step 2: Convert to fraction form
    208.21/312.08 = 139.71/x
  3. Step 3: Cross multiply
    208.21x = 312.08 × 139.71
  4. Step 4: Simplify right side
    208.21x = 43,600.70
  5. Step 5: Solve for x
    x = 43,600.70/208.21
  6. Step 6: Final answer
    x = 209.41

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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.