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Finding the Fourth Proportional to 20.85, 28.80 and 16.80

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Solution

The fourth proportional to 20.85, 28.80 and 16.80 is: 23.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.85 : 28.80 = 16.80 : x
  2. Step 2: Convert to fraction form
    20.85/28.80 = 16.80/x
  3. Step 3: Cross multiply
    20.85x = 28.80 × 16.80
  4. Step 4: Simplify right side
    20.85x = 483.84
  5. Step 5: Solve for x
    x = 483.84/20.85
  6. Step 6: Final answer
    x = 23.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.