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Finding the Fourth Proportional to 42.21, 63.20 and 21.86

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Solution

The fourth proportional to 42.21, 63.20 and 21.86 is: 32.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.21 : 63.20 = 21.86 : x
  2. Step 2: Convert to fraction form
    42.21/63.20 = 21.86/x
  3. Step 3: Cross multiply
    42.21x = 63.20 × 21.86
  4. Step 4: Simplify right side
    42.21x = 1,381.13
  5. Step 5: Solve for x
    x = 1,381.13/42.21
  6. Step 6: Final answer
    x = 32.72

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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.