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Finding the Fourth Proportional to 81.04, 111.84 and 72.80

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Solution

The fourth proportional to 81.04, 111.84 and 72.80 is: 100.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.04 : 111.84 = 72.80 : x
  2. Step 2: Convert to fraction form
    81.04/111.84 = 72.80/x
  3. Step 3: Cross multiply
    81.04x = 111.84 × 72.80
  4. Step 4: Simplify right side
    81.04x = 8,141.95
  5. Step 5: Solve for x
    x = 8,141.95/81.04
  6. Step 6: Final answer
    x = 100.47

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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.