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Finding the Fourth Proportional to 193.90, 291 and 85.78

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Solution

The fourth proportional to 193.90, 291 and 85.78 is: 128.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    193.90 : 291 = 85.78 : x
  2. Step 2: Convert to fraction form
    193.90/291 = 85.78/x
  3. Step 3: Cross multiply
    193.90x = 291 × 85.78
  4. Step 4: Simplify right side
    193.90x = 24,961.98
  5. Step 5: Solve for x
    x = 24,961.98/193.90
  6. Step 6: Final answer
    x = 128.74

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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.