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Finding the Fourth Proportional to 47.78, 71.65 and 18.91

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Solution

The fourth proportional to 47.78, 71.65 and 18.91 is: 28.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.78 : 71.65 = 18.91 : x
  2. Step 2: Convert to fraction form
    47.78/71.65 = 18.91/x
  3. Step 3: Cross multiply
    47.78x = 71.65 × 18.91
  4. Step 4: Simplify right side
    47.78x = 1,354.90
  5. Step 5: Solve for x
    x = 1,354.90/47.78
  6. Step 6: Final answer
    x = 28.36

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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.