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Finding the Fourth Proportional to 100.56, 138.72 and 61.68

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Solution

The fourth proportional to 100.56, 138.72 and 61.68 is: 85.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.56 : 138.72 = 61.68 : x
  2. Step 2: Convert to fraction form
    100.56/138.72 = 61.68/x
  3. Step 3: Cross multiply
    100.56x = 138.72 × 61.68
  4. Step 4: Simplify right side
    100.56x = 8,556.25
  5. Step 5: Solve for x
    x = 8,556.25/100.56
  6. Step 6: Final answer
    x = 85.09

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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.