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Finding the Fourth Proportional to 257.91, 386.89 and 84.57

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Solution

The fourth proportional to 257.91, 386.89 and 84.57 is: 126.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    257.91 : 386.89 = 84.57 : x
  2. Step 2: Convert to fraction form
    257.91/386.89 = 84.57/x
  3. Step 3: Cross multiply
    257.91x = 386.89 × 84.57
  4. Step 4: Simplify right side
    257.91x = 32,719.29
  5. Step 5: Solve for x
    x = 32,719.29/257.91
  6. Step 6: Final answer
    x = 126.86

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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.