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Finding the Fourth Proportional to 101.12, 139.55 and 61.78

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Solution

The fourth proportional to 101.12, 139.55 and 61.78 is: 85.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.12 : 139.55 = 61.78 : x
  2. Step 2: Convert to fraction form
    101.12/139.55 = 61.78/x
  3. Step 3: Cross multiply
    101.12x = 139.55 × 61.78
  4. Step 4: Simplify right side
    101.12x = 8,621.40
  5. Step 5: Solve for x
    x = 8,621.40/101.12
  6. Step 6: Final answer
    x = 85.26

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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.