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Finding the Fourth Proportional to 138.80, 208.60 and 128.08

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Solution

The fourth proportional to 138.80, 208.60 and 128.08 is: 192.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.80 : 208.60 = 128.08 : x
  2. Step 2: Convert to fraction form
    138.80/208.60 = 128.08/x
  3. Step 3: Cross multiply
    138.80x = 208.60 × 128.08
  4. Step 4: Simplify right side
    138.80x = 26,717.49
  5. Step 5: Solve for x
    x = 26,717.49/138.80
  6. Step 6: Final answer
    x = 192.49

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.