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Finding the Fourth Proportional to 42.15, 63.17 and 21.85

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Solution

The fourth proportional to 42.15, 63.17 and 21.85 is: 32.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.15 : 63.17 = 21.85 : x
  2. Step 2: Convert to fraction form
    42.15/63.17 = 21.85/x
  3. Step 3: Cross multiply
    42.15x = 63.17 × 21.85
  4. Step 4: Simplify right side
    42.15x = 1,380.26
  5. Step 5: Solve for x
    x = 1,380.26/42.15
  6. Step 6: Final answer
    x = 32.75

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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.