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Finding the Fourth Proportional to 128.44, 177.12 and 86.38

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Solution

The fourth proportional to 128.44, 177.12 and 86.38 is: 119.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.44 : 177.12 = 86.38 : x
  2. Step 2: Convert to fraction form
    128.44/177.12 = 86.38/x
  3. Step 3: Cross multiply
    128.44x = 177.12 × 86.38
  4. Step 4: Simplify right side
    128.44x = 15,299.46
  5. Step 5: Solve for x
    x = 15,299.46/128.44
  6. Step 6: Final answer
    x = 119.12

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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.