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Finding the Fourth Proportional to 39.08, 58.58 and 20.78

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Solution

The fourth proportional to 39.08, 58.58 and 20.78 is: 31.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.08 : 58.58 = 20.78 : x
  2. Step 2: Convert to fraction form
    39.08/58.58 = 20.78/x
  3. Step 3: Cross multiply
    39.08x = 58.58 × 20.78
  4. Step 4: Simplify right side
    39.08x = 1,217.29
  5. Step 5: Solve for x
    x = 1,217.29/39.08
  6. Step 6: Final answer
    x = 31.15

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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.