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Finding the Fourth Proportional to 485.54, 728.31 and 138.91

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Solution

The fourth proportional to 485.54, 728.31 and 138.91 is: 208.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.54 : 728.31 = 138.91 : x
  2. Step 2: Convert to fraction form
    485.54/728.31 = 138.91/x
  3. Step 3: Cross multiply
    485.54x = 728.31 × 138.91
  4. Step 4: Simplify right side
    485.54x = 101,169.54
  5. Step 5: Solve for x
    x = 101,169.54/485.54
  6. Step 6: Final answer
    x = 208.37

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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.