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Finding the Fourth Proportional to 385.78, 578.64 and 111.86

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Solution

The fourth proportional to 385.78, 578.64 and 111.86 is: 167.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    385.78 : 578.64 = 111.86 : x
  2. Step 2: Convert to fraction form
    385.78/578.64 = 111.86/x
  3. Step 3: Cross multiply
    385.78x = 578.64 × 111.86
  4. Step 4: Simplify right side
    385.78x = 64,726.67
  5. Step 5: Solve for x
    x = 64,726.67/385.78
  6. Step 6: Final answer
    x = 167.78

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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.