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Finding the Fourth Proportional to 38.90, 58.34 and 21.78

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Solution

The fourth proportional to 38.90, 58.34 and 21.78 is: 32.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.90 : 58.34 = 21.78 : x
  2. Step 2: Convert to fraction form
    38.90/58.34 = 21.78/x
  3. Step 3: Cross multiply
    38.90x = 58.34 × 21.78
  4. Step 4: Simplify right side
    38.90x = 1,270.65
  5. Step 5: Solve for x
    x = 1,270.65/38.90
  6. Step 6: Final answer
    x = 32.66

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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.