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Finding the Fourth Proportional to 138.18, 190.86 and 128.28

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Solution

The fourth proportional to 138.18, 190.86 and 128.28 is: 177.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.18 : 190.86 = 128.28 : x
  2. Step 2: Convert to fraction form
    138.18/190.86 = 128.28/x
  3. Step 3: Cross multiply
    138.18x = 190.86 × 128.28
  4. Step 4: Simplify right side
    138.18x = 24,483.52
  5. Step 5: Solve for x
    x = 24,483.52/138.18
  6. Step 6: Final answer
    x = 177.19

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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.