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Finding the Fourth Proportional to 728.21, 1,091.25 and 398.87

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Solution

The fourth proportional to 728.21, 1,091.25 and 398.87 is: 597.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.21 : 1,091.25 = 398.87 : x
  2. Step 2: Convert to fraction form
    728.21/1,091.25 = 398.87/x
  3. Step 3: Cross multiply
    728.21x = 1,091.25 × 398.87
  4. Step 4: Simplify right side
    728.21x = 435,261.43
  5. Step 5: Solve for x
    x = 435,261.43/728.21
  6. Step 6: Final answer
    x = 597.72

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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.