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Finding the Fourth Proportional to 128.79, 193.31 and 80.79

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Solution

The fourth proportional to 128.79, 193.31 and 80.79 is: 121.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.79 : 193.31 = 80.79 : x
  2. Step 2: Convert to fraction form
    128.79/193.31 = 80.79/x
  3. Step 3: Cross multiply
    128.79x = 193.31 × 80.79
  4. Step 4: Simplify right side
    128.79x = 15,617.51
  5. Step 5: Solve for x
    x = 15,617.51/128.79
  6. Step 6: Final answer
    x = 121.26

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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.