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Finding the Fourth Proportional to 385.90, 578.78 and 142.50

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Solution

The fourth proportional to 385.90, 578.78 and 142.50 is: 213.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    385.90 : 578.78 = 142.50 : x
  2. Step 2: Convert to fraction form
    385.90/578.78 = 142.50/x
  3. Step 3: Cross multiply
    385.90x = 578.78 × 142.50
  4. Step 4: Simplify right side
    385.90x = 82,476.15
  5. Step 5: Solve for x
    x = 82,476.15/385.90
  6. Step 6: Final answer
    x = 213.72

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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.