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Finding the Fourth Proportional to 67.20, 100.80 and 21.56

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Solution

The fourth proportional to 67.20, 100.80 and 21.56 is: 32.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    67.20 : 100.80 = 21.56 : x
  2. Step 2: Convert to fraction form
    67.20/100.80 = 21.56/x
  3. Step 3: Cross multiply
    67.20x = 100.80 × 21.56
  4. Step 4: Simplify right side
    67.20x = 2,173.25
  5. Step 5: Solve for x
    x = 2,173.25/67.20
  6. Step 6: Final answer
    x = 32.34

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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.