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Finding the Fourth Proportional to 71.78, 107.67 and 31.20

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Solution

The fourth proportional to 71.78, 107.67 and 31.20 is: 46.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    71.78 : 107.67 = 31.20 : x
  2. Step 2: Convert to fraction form
    71.78/107.67 = 31.20/x
  3. Step 3: Cross multiply
    71.78x = 107.67 × 31.20
  4. Step 4: Simplify right side
    71.78x = 3,359.30
  5. Step 5: Solve for x
    x = 3,359.30/71.78
  6. Step 6: Final answer
    x = 46.80

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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.