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Finding the Fourth Proportional to 485.95, 728.78 and 139.26

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Solution

The fourth proportional to 485.95, 728.78 and 139.26 is: 208.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.95 : 728.78 = 139.26 : x
  2. Step 2: Convert to fraction form
    485.95/728.78 = 139.26/x
  3. Step 3: Cross multiply
    485.95x = 728.78 × 139.26
  4. Step 4: Simplify right side
    485.95x = 101,489.90
  5. Step 5: Solve for x
    x = 101,489.90/485.95
  6. Step 6: Final answer
    x = 208.85

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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.