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Finding the Fourth Proportional to 81.15, 112.10 and 72.45

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Solution

The fourth proportional to 81.15, 112.10 and 72.45 is: 100.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.15 : 112.10 = 72.45 : x
  2. Step 2: Convert to fraction form
    81.15/112.10 = 72.45/x
  3. Step 3: Cross multiply
    81.15x = 112.10 × 72.45
  4. Step 4: Simplify right side
    81.15x = 8,121.28
  5. Step 5: Solve for x
    x = 8,121.28/81.15
  6. Step 6: Final answer
    x = 100.08

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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.