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Finding the Fourth Proportional to 261.80, 391.90 and 261.80

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Solution

The fourth proportional to 261.80, 391.90 and 261.80 is: 391.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.80 : 391.90 = 261.80 : x
  2. Step 2: Convert to fraction form
    261.80/391.90 = 261.80/x
  3. Step 3: Cross multiply
    261.80x = 391.90 × 261.80
  4. Step 4: Simplify right side
    261.80x = 102,599.42
  5. Step 5: Solve for x
    x = 102,599.42/261.80
  6. Step 6: Final answer
    x = 391.90

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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.