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Finding the Fourth Proportional to 261.15, 391.11 and 199.79

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Solution

The fourth proportional to 261.15, 391.11 and 199.79 is: 299.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.15 : 391.11 = 199.79 : x
  2. Step 2: Convert to fraction form
    261.15/391.11 = 199.79/x
  3. Step 3: Cross multiply
    261.15x = 391.11 × 199.79
  4. Step 4: Simplify right side
    261.15x = 78,139.87
  5. Step 5: Solve for x
    x = 78,139.87/261.15
  6. Step 6: Final answer
    x = 299.21

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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.