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Finding the Fourth Proportional to 100.17, 138.06 and 81.63

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Solution

The fourth proportional to 100.17, 138.06 and 81.63 is: 112.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.17 : 138.06 = 81.63 : x
  2. Step 2: Convert to fraction form
    100.17/138.06 = 81.63/x
  3. Step 3: Cross multiply
    100.17x = 138.06 × 81.63
  4. Step 4: Simplify right side
    100.17x = 11,269.84
  5. Step 5: Solve for x
    x = 11,269.84/100.17
  6. Step 6: Final answer
    x = 112.51

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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.