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Finding the Fourth Proportional to 128.98, 193.20 and 109.72

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Solution

The fourth proportional to 128.98, 193.20 and 109.72 is: 164.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.98 : 193.20 = 109.72 : x
  2. Step 2: Convert to fraction form
    128.98/193.20 = 109.72/x
  3. Step 3: Cross multiply
    128.98x = 193.20 × 109.72
  4. Step 4: Simplify right side
    128.98x = 21,197.90
  5. Step 5: Solve for x
    x = 21,197.90/128.98
  6. Step 6: Final answer
    x = 164.35

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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.