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Finding the Fourth Proportional to 728.31, 1,003.99 and 640.15

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Solution

The fourth proportional to 728.31, 1,003.99 and 640.15 is: 882.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.31 : 1,003.99 = 640.15 : x
  2. Step 2: Convert to fraction form
    728.31/1,003.99 = 640.15/x
  3. Step 3: Cross multiply
    728.31x = 1,003.99 × 640.15
  4. Step 4: Simplify right side
    728.31x = 642,704.20
  5. Step 5: Solve for x
    x = 642,704.20/728.31
  6. Step 6: Final answer
    x = 882.46

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.