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Finding the Fourth Proportional to 72.18, 108.18 and 55

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Solution

The fourth proportional to 72.18, 108.18 and 55 is: 82.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.18 : 108.18 = 55 : x
  2. Step 2: Convert to fraction form
    72.18/108.18 = 55/x
  3. Step 3: Cross multiply
    72.18x = 108.18 × 55
  4. Step 4: Simplify right side
    72.18x = 5,949.90
  5. Step 5: Solve for x
    x = 5,949.90/72.18
  6. Step 6: Final answer
    x = 82.43

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.