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Finding the Fourth Proportional to 39.20, 58.68 and 21.12

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Solution

The fourth proportional to 39.20, 58.68 and 21.12 is: 31.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.20 : 58.68 = 21.12 : x
  2. Step 2: Convert to fraction form
    39.20/58.68 = 21.12/x
  3. Step 3: Cross multiply
    39.20x = 58.68 × 21.12
  4. Step 4: Simplify right side
    39.20x = 1,239.32
  5. Step 5: Solve for x
    x = 1,239.32/39.20
  6. Step 6: Final answer
    x = 31.62

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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.