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Finding the Fourth Proportional to 28.72, 43.07 and 21.12

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Solution

The fourth proportional to 28.72, 43.07 and 21.12 is: 31.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.72 : 43.07 = 21.12 : x
  2. Step 2: Convert to fraction form
    28.72/43.07 = 21.12/x
  3. Step 3: Cross multiply
    28.72x = 43.07 × 21.12
  4. Step 4: Simplify right side
    28.72x = 909.69
  5. Step 5: Solve for x
    x = 909.69/28.72
  6. Step 6: Final answer
    x = 31.68

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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.