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Finding the Fourth Proportional to 38.91, 58.40 and 20.89

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Solution

The fourth proportional to 38.91, 58.40 and 20.89 is: 31.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.91 : 58.40 = 20.89 : x
  2. Step 2: Convert to fraction form
    38.91/58.40 = 20.89/x
  3. Step 3: Cross multiply
    38.91x = 58.40 × 20.89
  4. Step 4: Simplify right side
    38.91x = 1,219.98
  5. Step 5: Solve for x
    x = 1,219.98/38.91
  6. Step 6: Final answer
    x = 31.35

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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.