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Finding the Fourth Proportional to 386.11, 579.39 and 142.80

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Solution

The fourth proportional to 386.11, 579.39 and 142.80 is: 214.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.11 : 579.39 = 142.80 : x
  2. Step 2: Convert to fraction form
    386.11/579.39 = 142.80/x
  3. Step 3: Cross multiply
    386.11x = 579.39 × 142.80
  4. Step 4: Simplify right side
    386.11x = 82,736.18
  5. Step 5: Solve for x
    x = 82,736.18/386.11
  6. Step 6: Final answer
    x = 214.28

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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.