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Finding the Fourth Proportional to 840.78, 1,261.20 and 263.70

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Solution

The fourth proportional to 840.78, 1,261.20 and 263.70 is: 395.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.78 : 1,261.20 = 263.70 : x
  2. Step 2: Convert to fraction form
    840.78/1,261.20 = 263.70/x
  3. Step 3: Cross multiply
    840.78x = 1,261.20 × 263.70
  4. Step 4: Simplify right side
    840.78x = 332,578.44
  5. Step 5: Solve for x
    x = 332,578.44/840.78
  6. Step 6: Final answer
    x = 395.56

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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.