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Finding the Fourth Proportional to 100.09, 138.05 and 81.56

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Solution

The fourth proportional to 100.09, 138.05 and 81.56 is: 112.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.09 : 138.05 = 81.56 : x
  2. Step 2: Convert to fraction form
    100.09/138.05 = 81.56/x
  3. Step 3: Cross multiply
    100.09x = 138.05 × 81.56
  4. Step 4: Simplify right side
    100.09x = 11,259.28
  5. Step 5: Solve for x
    x = 11,259.28/100.09
  6. Step 6: Final answer
    x = 112.50

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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.