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Finding the Fourth Proportional to 21.58, 32.39 and 19.90

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Solution

The fourth proportional to 21.58, 32.39 and 19.90 is: 29.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.58 : 32.39 = 19.90 : x
  2. Step 2: Convert to fraction form
    21.58/32.39 = 19.90/x
  3. Step 3: Cross multiply
    21.58x = 32.39 × 19.90
  4. Step 4: Simplify right side
    21.58x = 644.56
  5. Step 5: Solve for x
    x = 644.56/21.58
  6. Step 6: Final answer
    x = 29.87

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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.