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Finding the Fourth Proportional to 1,239.89, 1,711 and 680.35

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Solution

The fourth proportional to 1,239.89, 1,711 and 680.35 is: 938.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.89 : 1,711 = 680.35 : x
  2. Step 2: Convert to fraction form
    1,239.89/1,711 = 680.35/x
  3. Step 3: Cross multiply
    1,239.89x = 1,711 × 680.35
  4. Step 4: Simplify right side
    1,239.89x = 1,164,078.85
  5. Step 5: Solve for x
    x = 1,164,078.85/1,239.89
  6. Step 6: Final answer
    x = 938.86

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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.