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Finding the Fourth Proportional to 67.20, 100.76 and 21.55

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Solution

The fourth proportional to 67.20, 100.76 and 21.55 is: 32.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    67.20 : 100.76 = 21.55 : x
  2. Step 2: Convert to fraction form
    67.20/100.76 = 21.55/x
  3. Step 3: Cross multiply
    67.20x = 100.76 × 21.55
  4. Step 4: Simplify right side
    67.20x = 2,171.38
  5. Step 5: Solve for x
    x = 2,171.38/67.20
  6. Step 6: Final answer
    x = 32.31

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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.