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Finding the Fourth Proportional to 128.82, 177.84 and 99.66

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Solution

The fourth proportional to 128.82, 177.84 and 99.66 is: 137.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.82 : 177.84 = 99.66 : x
  2. Step 2: Convert to fraction form
    128.82/177.84 = 99.66/x
  3. Step 3: Cross multiply
    128.82x = 177.84 × 99.66
  4. Step 4: Simplify right side
    128.82x = 17,723.53
  5. Step 5: Solve for x
    x = 17,723.53/128.82
  6. Step 6: Final answer
    x = 137.58

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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.