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Finding the Fourth Proportional to 103.72, 143.20 and 81.84

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Solution

The fourth proportional to 103.72, 143.20 and 81.84 is: 112.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.72 : 143.20 = 81.84 : x
  2. Step 2: Convert to fraction form
    103.72/143.20 = 81.84/x
  3. Step 3: Cross multiply
    103.72x = 143.20 × 81.84
  4. Step 4: Simplify right side
    103.72x = 11,719.49
  5. Step 5: Solve for x
    x = 11,719.49/103.72
  6. Step 6: Final answer
    x = 112.99

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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.