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Finding the Fourth Proportional to 128.31, 177.02 and 111.91

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Solution

The fourth proportional to 128.31, 177.02 and 111.91 is: 154.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.31 : 177.02 = 111.91 : x
  2. Step 2: Convert to fraction form
    128.31/177.02 = 111.91/x
  3. Step 3: Cross multiply
    128.31x = 177.02 × 111.91
  4. Step 4: Simplify right side
    128.31x = 19,809.42
  5. Step 5: Solve for x
    x = 19,809.42/128.31
  6. Step 6: Final answer
    x = 154.39

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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.