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Finding the Fourth Proportional to 128.37, 177.29 and 87.09

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Solution

The fourth proportional to 128.37, 177.29 and 87.09 is: 120.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.37 : 177.29 = 87.09 : x
  2. Step 2: Convert to fraction form
    128.37/177.29 = 87.09/x
  3. Step 3: Cross multiply
    128.37x = 177.29 × 87.09
  4. Step 4: Simplify right side
    128.37x = 15,439.75
  5. Step 5: Solve for x
    x = 15,439.75/128.37
  6. Step 6: Final answer
    x = 120.28

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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.