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Finding the Fourth Proportional to 128.72, 193.13 and 67.90

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Solution

The fourth proportional to 128.72, 193.13 and 67.90 is: 101.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.72 : 193.13 = 67.90 : x
  2. Step 2: Convert to fraction form
    128.72/193.13 = 67.90/x
  3. Step 3: Cross multiply
    128.72x = 193.13 × 67.90
  4. Step 4: Simplify right side
    128.72x = 13,113.53
  5. Step 5: Solve for x
    x = 13,113.53/128.72
  6. Step 6: Final answer
    x = 101.88

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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.