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Finding the Fourth Proportional to 102.78, 141.80 and 80.91

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Solution

The fourth proportional to 102.78, 141.80 and 80.91 is: 111.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.78 : 141.80 = 80.91 : x
  2. Step 2: Convert to fraction form
    102.78/141.80 = 80.91/x
  3. Step 3: Cross multiply
    102.78x = 141.80 × 80.91
  4. Step 4: Simplify right side
    102.78x = 11,471.92
  5. Step 5: Solve for x
    x = 11,471.92/102.78
  6. Step 6: Final answer
    x = 111.62

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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.