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Finding the Fourth Proportional to 320.78, 480.78 and 138.12

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Solution

The fourth proportional to 320.78, 480.78 and 138.12 is: 207.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    320.78 : 480.78 = 138.12 : x
  2. Step 2: Convert to fraction form
    320.78/480.78 = 138.12/x
  3. Step 3: Cross multiply
    320.78x = 480.78 × 138.12
  4. Step 4: Simplify right side
    320.78x = 66,405.33
  5. Step 5: Solve for x
    x = 66,405.33/320.78
  6. Step 6: Final answer
    x = 207.02

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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.