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Finding the Fourth Proportional to 3,939.90, 5,909.90 and 978.34

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Solution

The fourth proportional to 3,939.90, 5,909.90 and 978.34 is: 1,467.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    3,939.90 : 5,909.90 = 978.34 : x
  2. Step 2: Convert to fraction form
    3,939.90/5,909.90 = 978.34/x
  3. Step 3: Cross multiply
    3,939.90x = 5,909.90 × 978.34
  4. Step 4: Simplify right side
    3,939.90x = 5,781,891.57
  5. Step 5: Solve for x
    x = 5,781,891.57/3,939.90
  6. Step 6: Final answer
    x = 1,467.52

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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.