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Finding the Fourth Proportional to 101.20, 139.63 and 61.87

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Solution

The fourth proportional to 101.20, 139.63 and 61.87 is: 85.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.20 : 139.63 = 61.87 : x
  2. Step 2: Convert to fraction form
    101.20/139.63 = 61.87/x
  3. Step 3: Cross multiply
    101.20x = 139.63 × 61.87
  4. Step 4: Simplify right side
    101.20x = 8,638.91
  5. Step 5: Solve for x
    x = 8,638.91/101.20
  6. Step 6: Final answer
    x = 85.36

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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.