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Finding the Fourth Proportional to 47.78, 71.61 and 18.85

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Solution

The fourth proportional to 47.78, 71.61 and 18.85 is: 28.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.78 : 71.61 = 18.85 : x
  2. Step 2: Convert to fraction form
    47.78/71.61 = 18.85/x
  3. Step 3: Cross multiply
    47.78x = 71.61 × 18.85
  4. Step 4: Simplify right side
    47.78x = 1,349.61
  5. Step 5: Solve for x
    x = 1,349.61/47.78
  6. Step 6: Final answer
    x = 28.25

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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.