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Finding the Fourth Proportional to 485.86, 728.91 and 139.19

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Solution

The fourth proportional to 485.86, 728.91 and 139.19 is: 208.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.86 : 728.91 = 139.19 : x
  2. Step 2: Convert to fraction form
    485.86/728.91 = 139.19/x
  3. Step 3: Cross multiply
    485.86x = 728.91 × 139.19
  4. Step 4: Simplify right side
    485.86x = 101,456.98
  5. Step 5: Solve for x
    x = 101,456.98/485.86
  6. Step 6: Final answer
    x = 208.82

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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.