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Finding the Fourth Proportional to 389.91, 538.31 and 257.34

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Solution

The fourth proportional to 389.91, 538.31 and 257.34 is: 355.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    389.91 : 538.31 = 257.34 : x
  2. Step 2: Convert to fraction form
    389.91/538.31 = 257.34/x
  3. Step 3: Cross multiply
    389.91x = 538.31 × 257.34
  4. Step 4: Simplify right side
    389.91x = 138,527.41
  5. Step 5: Solve for x
    x = 138,527.41/389.91
  6. Step 6: Final answer
    x = 355.28

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.