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Finding the Fourth Proportional to 485.42, 728.01 and 138.68

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Solution

The fourth proportional to 485.42, 728.01 and 138.68 is: 207.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.42 : 728.01 = 138.68 : x
  2. Step 2: Convert to fraction form
    485.42/728.01 = 138.68/x
  3. Step 3: Cross multiply
    485.42x = 728.01 × 138.68
  4. Step 4: Simplify right side
    485.42x = 100,959.73
  5. Step 5: Solve for x
    x = 100,959.73/485.42
  6. Step 6: Final answer
    x = 207.98

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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.