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Finding the Fourth Proportional to 1,285.72, 1,928.64 and 408.31

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Solution

The fourth proportional to 1,285.72, 1,928.64 and 408.31 is: 612.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,285.72 : 1,928.64 = 408.31 : x
  2. Step 2: Convert to fraction form
    1,285.72/1,928.64 = 408.31/x
  3. Step 3: Cross multiply
    1,285.72x = 1,928.64 × 408.31
  4. Step 4: Simplify right side
    1,285.72x = 787,477.41
  5. Step 5: Solve for x
    x = 787,477.41/1,285.72
  6. Step 6: Final answer
    x = 612.48

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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.