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Finding the Fourth Proportional to 128.31, 176.96 and 91.40

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Solution

The fourth proportional to 128.31, 176.96 and 91.40 is: 126.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.31 : 176.96 = 91.40 : x
  2. Step 2: Convert to fraction form
    128.31/176.96 = 91.40/x
  3. Step 3: Cross multiply
    128.31x = 176.96 × 91.40
  4. Step 4: Simplify right side
    128.31x = 16,174.14
  5. Step 5: Solve for x
    x = 16,174.14/128.31
  6. Step 6: Final answer
    x = 126.06

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.