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Finding the Fourth Proportional to 77.90, 107.39 and 61.49

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Solution

The fourth proportional to 77.90, 107.39 and 61.49 is: 84.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.90 : 107.39 = 61.49 : x
  2. Step 2: Convert to fraction form
    77.90/107.39 = 61.49/x
  3. Step 3: Cross multiply
    77.90x = 107.39 × 61.49
  4. Step 4: Simplify right side
    77.90x = 6,603.83
  5. Step 5: Solve for x
    x = 6,603.83/77.90
  6. Step 6: Final answer
    x = 84.78

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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.