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Finding the Fourth Proportional to 28.21, 42.20 and 19.66

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Solution

The fourth proportional to 28.21, 42.20 and 19.66 is: 29.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.21 : 42.20 = 19.66 : x
  2. Step 2: Convert to fraction form
    28.21/42.20 = 19.66/x
  3. Step 3: Cross multiply
    28.21x = 42.20 × 19.66
  4. Step 4: Simplify right side
    28.21x = 829.65
  5. Step 5: Solve for x
    x = 829.65/28.21
  6. Step 6: Final answer
    x = 29.41

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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.