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Finding the Fourth Proportional to 78.21, 107.90 and 50.61

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Solution

The fourth proportional to 78.21, 107.90 and 50.61 is: 69.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.21 : 107.90 = 50.61 : x
  2. Step 2: Convert to fraction form
    78.21/107.90 = 50.61/x
  3. Step 3: Cross multiply
    78.21x = 107.90 × 50.61
  4. Step 4: Simplify right side
    78.21x = 5,460.57
  5. Step 5: Solve for x
    x = 5,460.57/78.21
  6. Step 6: Final answer
    x = 69.82

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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.