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Finding the Fourth Proportional to 42.21, 63.24 and 21.87

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Solution

The fourth proportional to 42.21, 63.24 and 21.87 is: 32.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.21 : 63.24 = 21.87 : x
  2. Step 2: Convert to fraction form
    42.21/63.24 = 21.87/x
  3. Step 3: Cross multiply
    42.21x = 63.24 × 21.87
  4. Step 4: Simplify right side
    42.21x = 1,383.06
  5. Step 5: Solve for x
    x = 1,383.06/42.21
  6. Step 6: Final answer
    x = 32.77

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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.