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Finding the Fourth Proportional to 212.74, 318.54 and 139.43

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Solution

The fourth proportional to 212.74, 318.54 and 139.43 is: 208.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.74 : 318.54 = 139.43 : x
  2. Step 2: Convert to fraction form
    212.74/318.54 = 139.43/x
  3. Step 3: Cross multiply
    212.74x = 318.54 × 139.43
  4. Step 4: Simplify right side
    212.74x = 44,414.83
  5. Step 5: Solve for x
    x = 44,414.83/212.74
  6. Step 6: Final answer
    x = 208.78

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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.