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Finding the Fourth Proportional to 39.90, 59.82 and 21.80

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Solution

The fourth proportional to 39.90, 59.82 and 21.80 is: 32.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.90 : 59.82 = 21.80 : x
  2. Step 2: Convert to fraction form
    39.90/59.82 = 21.80/x
  3. Step 3: Cross multiply
    39.90x = 59.82 × 21.80
  4. Step 4: Simplify right side
    39.90x = 1,304.08
  5. Step 5: Solve for x
    x = 1,304.08/39.90
  6. Step 6: Final answer
    x = 32.68

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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.