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Finding the Fourth Proportional to 128.48, 177.20 and 91.76

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Solution

The fourth proportional to 128.48, 177.20 and 91.76 is: 126.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.48 : 177.20 = 91.76 : x
  2. Step 2: Convert to fraction form
    128.48/177.20 = 91.76/x
  3. Step 3: Cross multiply
    128.48x = 177.20 × 91.76
  4. Step 4: Simplify right side
    128.48x = 16,259.87
  5. Step 5: Solve for x
    x = 16,259.87/128.48
  6. Step 6: Final answer
    x = 126.56

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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.