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Finding the Fourth Proportional to 128.85, 177.89 and 89.57

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Solution

The fourth proportional to 128.85, 177.89 and 89.57 is: 123.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.85 : 177.89 = 89.57 : x
  2. Step 2: Convert to fraction form
    128.85/177.89 = 89.57/x
  3. Step 3: Cross multiply
    128.85x = 177.89 × 89.57
  4. Step 4: Simplify right side
    128.85x = 15,932.27
  5. Step 5: Solve for x
    x = 15,932.27/128.85
  6. Step 6: Final answer
    x = 123.65

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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.