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Finding the Fourth Proportional to 261.28, 391.60 and 139.36

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Solution

The fourth proportional to 261.28, 391.60 and 139.36 is: 208.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.28 : 391.60 = 139.36 : x
  2. Step 2: Convert to fraction form
    261.28/391.60 = 139.36/x
  3. Step 3: Cross multiply
    261.28x = 391.60 × 139.36
  4. Step 4: Simplify right side
    261.28x = 54,573.38
  5. Step 5: Solve for x
    x = 54,573.38/261.28
  6. Step 6: Final answer
    x = 208.87

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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.