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Finding the Fourth Proportional to 386.12, 578.60 and 142.40

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Solution

The fourth proportional to 386.12, 578.60 and 142.40 is: 213.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.12 : 578.60 = 142.40 : x
  2. Step 2: Convert to fraction form
    386.12/578.60 = 142.40/x
  3. Step 3: Cross multiply
    386.12x = 578.60 × 142.40
  4. Step 4: Simplify right side
    386.12x = 82,392.64
  5. Step 5: Solve for x
    x = 82,392.64/386.12
  6. Step 6: Final answer
    x = 213.39

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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.