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Finding the Fourth Proportional to 257.10, 386.49 and 211.78

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Solution

The fourth proportional to 257.10, 386.49 and 211.78 is: 318.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.10 : 386.49 = 211.78 : x
  2. Step 2: Convert to fraction form
    257.10/386.49 = 211.78/x
  3. Step 3: Cross multiply
    257.10x = 386.49 × 211.78
  4. Step 4: Simplify right side
    257.10x = 81,850.85
  5. Step 5: Solve for x
    x = 81,850.85/257.10
  6. Step 6: Final answer
    x = 318.36

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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.