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Finding the Fourth Proportional to 39.30, 58.90 and 21.25

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Solution

The fourth proportional to 39.30, 58.90 and 21.25 is: 31.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.30 : 58.90 = 21.25 : x
  2. Step 2: Convert to fraction form
    39.30/58.90 = 21.25/x
  3. Step 3: Cross multiply
    39.30x = 58.90 × 21.25
  4. Step 4: Simplify right side
    39.30x = 1,251.63
  5. Step 5: Solve for x
    x = 1,251.63/39.30
  6. Step 6: Final answer
    x = 31.85

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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.