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Finding the Fourth Proportional to 386.40, 579.36 and 142.80

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Solution

The fourth proportional to 386.40, 579.36 and 142.80 is: 214.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    386.40 : 579.36 = 142.80 : x
  2. Step 2: Convert to fraction form
    386.40/579.36 = 142.80/x
  3. Step 3: Cross multiply
    386.40x = 579.36 × 142.80
  4. Step 4: Simplify right side
    386.40x = 82,732.61
  5. Step 5: Solve for x
    x = 82,732.61/386.40
  6. Step 6: Final answer
    x = 214.11

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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.