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Finding the Fourth Proportional to 261.31, 392.20 and 139.67

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Solution

The fourth proportional to 261.31, 392.20 and 139.67 is: 209.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.31 : 392.20 = 139.67 : x
  2. Step 2: Convert to fraction form
    261.31/392.20 = 139.67/x
  3. Step 3: Cross multiply
    261.31x = 392.20 × 139.67
  4. Step 4: Simplify right side
    261.31x = 54,778.57
  5. Step 5: Solve for x
    x = 54,778.57/261.31
  6. Step 6: Final answer
    x = 209.63

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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.