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Finding the Fourth Proportional to 1,285.92, 1,929 and 420.28

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Solution

The fourth proportional to 1,285.92, 1,929 and 420.28 is: 630.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,285.92 : 1,929 = 420.28 : x
  2. Step 2: Convert to fraction form
    1,285.92/1,929 = 420.28/x
  3. Step 3: Cross multiply
    1,285.92x = 1,929 × 420.28
  4. Step 4: Simplify right side
    1,285.92x = 810,720.12
  5. Step 5: Solve for x
    x = 810,720.12/1,285.92
  6. Step 6: Final answer
    x = 630.46

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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.