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Finding the Fourth Proportional to 120.78, 180.96 and 103.74

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Solution

The fourth proportional to 120.78, 180.96 and 103.74 is: 155.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.78 : 180.96 = 103.74 : x
  2. Step 2: Convert to fraction form
    120.78/180.96 = 103.74/x
  3. Step 3: Cross multiply
    120.78x = 180.96 × 103.74
  4. Step 4: Simplify right side
    120.78x = 18,772.79
  5. Step 5: Solve for x
    x = 18,772.79/120.78
  6. Step 6: Final answer
    x = 155.43

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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.