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Finding the Fourth Proportional to 128.69, 177.49 and 82.11

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Solution

The fourth proportional to 128.69, 177.49 and 82.11 is: 113.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.69 : 177.49 = 82.11 : x
  2. Step 2: Convert to fraction form
    128.69/177.49 = 82.11/x
  3. Step 3: Cross multiply
    128.69x = 177.49 × 82.11
  4. Step 4: Simplify right side
    128.69x = 14,574.47
  5. Step 5: Solve for x
    x = 14,574.47/128.69
  6. Step 6: Final answer
    x = 113.25

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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.