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Finding the Fourth Proportional to 728.70, 1,091.61 and 420.36

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Solution

The fourth proportional to 728.70, 1,091.61 and 420.36 is: 629.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.70 : 1,091.61 = 420.36 : x
  2. Step 2: Convert to fraction form
    728.70/1,091.61 = 420.36/x
  3. Step 3: Cross multiply
    728.70x = 1,091.61 × 420.36
  4. Step 4: Simplify right side
    728.70x = 458,869.18
  5. Step 5: Solve for x
    x = 458,869.18/728.70
  6. Step 6: Final answer
    x = 629.71

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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.