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Finding the Fourth Proportional to 781, 1,077.78 and 505.48

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Solution

The fourth proportional to 781, 1,077.78 and 505.48 is: 697.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    781 : 1,077.78 = 505.48 : x
  2. Step 2: Convert to fraction form
    781/1,077.78 = 505.48/x
  3. Step 3: Cross multiply
    781x = 1,077.78 × 505.48
  4. Step 4: Simplify right side
    781x = 544,796.23
  5. Step 5: Solve for x
    x = 544,796.23/781
  6. Step 6: Final answer
    x = 697.56

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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.