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Finding the Fourth Proportional to 386.39, 579.21 and 142.85

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Solution

The fourth proportional to 386.39, 579.21 and 142.85 is: 214.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.39 : 579.21 = 142.85 : x
  2. Step 2: Convert to fraction form
    386.39/579.21 = 142.85/x
  3. Step 3: Cross multiply
    386.39x = 579.21 × 142.85
  4. Step 4: Simplify right side
    386.39x = 82,740.15
  5. Step 5: Solve for x
    x = 82,740.15/386.39
  6. Step 6: Final answer
    x = 214.14

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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.