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Finding the Fourth Proportional to 128.98, 193.37 and 80.21

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Solution

The fourth proportional to 128.98, 193.37 and 80.21 is: 120.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.98 : 193.37 = 80.21 : x
  2. Step 2: Convert to fraction form
    128.98/193.37 = 80.21/x
  3. Step 3: Cross multiply
    128.98x = 193.37 × 80.21
  4. Step 4: Simplify right side
    128.98x = 15,510.21
  5. Step 5: Solve for x
    x = 15,510.21/128.98
  6. Step 6: Final answer
    x = 120.25

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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.