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Finding the Fourth Proportional to 47.90, 71.78 and 20.83

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Solution

The fourth proportional to 47.90, 71.78 and 20.83 is: 31.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.90 : 71.78 = 20.83 : x
  2. Step 2: Convert to fraction form
    47.90/71.78 = 20.83/x
  3. Step 3: Cross multiply
    47.90x = 71.78 × 20.83
  4. Step 4: Simplify right side
    47.90x = 1,495.18
  5. Step 5: Solve for x
    x = 1,495.18/47.90
  6. Step 6: Final answer
    x = 31.21

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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.