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Finding the Fourth Proportional to 1,280, 1,766.48 and 728

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Solution

The fourth proportional to 1,280, 1,766.48 and 728 is: 1,004.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280 : 1,766.48 = 728 : x
  2. Step 2: Convert to fraction form
    1,280/1,766.48 = 728/x
  3. Step 3: Cross multiply
    1,280x = 1,766.48 × 728
  4. Step 4: Simplify right side
    1,280x = 1,285,997.44
  5. Step 5: Solve for x
    x = 1,285,997.44/1,280
  6. Step 6: Final answer
    x = 1,004.69

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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.