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Finding the Fourth Proportional to 412.78, 619.12 and 138.80

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Solution

The fourth proportional to 412.78, 619.12 and 138.80 is: 208.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    412.78 : 619.12 = 138.80 : x
  2. Step 2: Convert to fraction form
    412.78/619.12 = 138.80/x
  3. Step 3: Cross multiply
    412.78x = 619.12 × 138.80
  4. Step 4: Simplify right side
    412.78x = 85,933.86
  5. Step 5: Solve for x
    x = 85,933.86/412.78
  6. Step 6: Final answer
    x = 208.18

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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.