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Finding the Fourth Proportional to 72.90, 108.81 and 54.81

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Solution

The fourth proportional to 72.90, 108.81 and 54.81 is: 81.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.90 : 108.81 = 54.81 : x
  2. Step 2: Convert to fraction form
    72.90/108.81 = 54.81/x
  3. Step 3: Cross multiply
    72.90x = 108.81 × 54.81
  4. Step 4: Simplify right side
    72.90x = 5,963.88
  5. Step 5: Solve for x
    x = 5,963.88/72.90
  6. Step 6: Final answer
    x = 81.81

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.