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Finding the Fourth Proportional to 261.91, 392.58 and 139.87

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Solution

The fourth proportional to 261.91, 392.58 and 139.87 is: 209.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.91 : 392.58 = 139.87 : x
  2. Step 2: Convert to fraction form
    261.91/392.58 = 139.87/x
  3. Step 3: Cross multiply
    261.91x = 392.58 × 139.87
  4. Step 4: Simplify right side
    261.91x = 54,910.16
  5. Step 5: Solve for x
    x = 54,910.16/261.91
  6. Step 6: Final answer
    x = 209.65

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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.