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Finding the Fourth Proportional to 485.74, 728.49 and 139.06

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Solution

The fourth proportional to 485.74, 728.49 and 139.06 is: 208.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.74 : 728.49 = 139.06 : x
  2. Step 2: Convert to fraction form
    485.74/728.49 = 139.06/x
  3. Step 3: Cross multiply
    485.74x = 728.49 × 139.06
  4. Step 4: Simplify right side
    485.74x = 101,303.82
  5. Step 5: Solve for x
    x = 101,303.82/485.74
  6. Step 6: Final answer
    x = 208.56

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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.