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Finding the Fourth Proportional to 212.89, 319.20 and 139.67

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Solution

The fourth proportional to 212.89, 319.20 and 139.67 is: 209.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.89 : 319.20 = 139.67 : x
  2. Step 2: Convert to fraction form
    212.89/319.20 = 139.67/x
  3. Step 3: Cross multiply
    212.89x = 319.20 × 139.67
  4. Step 4: Simplify right side
    212.89x = 44,581.97
  5. Step 5: Solve for x
    x = 44,581.97/212.89
  6. Step 6: Final answer
    x = 209.42

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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.