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Finding the Fourth Proportional to 61.45, 92.20 and 20.90

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Solution

The fourth proportional to 61.45, 92.20 and 20.90 is: 31.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.45 : 92.20 = 20.90 : x
  2. Step 2: Convert to fraction form
    61.45/92.20 = 20.90/x
  3. Step 3: Cross multiply
    61.45x = 92.20 × 20.90
  4. Step 4: Simplify right side
    61.45x = 1,926.98
  5. Step 5: Solve for x
    x = 1,926.98/61.45
  6. Step 6: Final answer
    x = 31.36

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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.