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Finding the Fourth Proportional to 40.90, 61.28 and 20.56

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Solution

The fourth proportional to 40.90, 61.28 and 20.56 is: 30.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    40.90 : 61.28 = 20.56 : x
  2. Step 2: Convert to fraction form
    40.90/61.28 = 20.56/x
  3. Step 3: Cross multiply
    40.90x = 61.28 × 20.56
  4. Step 4: Simplify right side
    40.90x = 1,259.92
  5. Step 5: Solve for x
    x = 1,259.92/40.90
  6. Step 6: Final answer
    x = 30.80

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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.