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Finding the Fourth Proportional to 22.80, 31.20 and 21.12

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Solution

The fourth proportional to 22.80, 31.20 and 21.12 is: 28.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    22.80 : 31.20 = 21.12 : x
  2. Step 2: Convert to fraction form
    22.80/31.20 = 21.12/x
  3. Step 3: Cross multiply
    22.80x = 31.20 × 21.12
  4. Step 4: Simplify right side
    22.80x = 658.94
  5. Step 5: Solve for x
    x = 658.94/22.80
  6. Step 6: Final answer
    x = 28.90

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.