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Finding the Fourth Proportional to 143.15, 197.55 and 81

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Solution

The fourth proportional to 143.15, 197.55 and 81 is: 111.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.15 : 197.55 = 81 : x
  2. Step 2: Convert to fraction form
    143.15/197.55 = 81/x
  3. Step 3: Cross multiply
    143.15x = 197.55 × 81
  4. Step 4: Simplify right side
    143.15x = 16,001.55
  5. Step 5: Solve for x
    x = 16,001.55/143.15
  6. Step 6: Final answer
    x = 111.78

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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.