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Finding the Fourth Proportional to 1,278.35, 1,920.94 and 693.78

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Solution

The fourth proportional to 1,278.35, 1,920.94 and 693.78 is: 1,042.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.35 : 1,920.94 = 693.78 : x
  2. Step 2: Convert to fraction form
    1,278.35/1,920.94 = 693.78/x
  3. Step 3: Cross multiply
    1,278.35x = 1,920.94 × 693.78
  4. Step 4: Simplify right side
    1,278.35x = 1,332,700.15
  5. Step 5: Solve for x
    x = 1,332,700.15/1,278.35
  6. Step 6: Final answer
    x = 1,042.52

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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.