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Finding the Fourth Proportional to 138.40, 208.75 and 129.40

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Solution

The fourth proportional to 138.40, 208.75 and 129.40 is: 195.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.40 : 208.75 = 129.40 : x
  2. Step 2: Convert to fraction form
    138.40/208.75 = 129.40/x
  3. Step 3: Cross multiply
    138.40x = 208.75 × 129.40
  4. Step 4: Simplify right side
    138.40x = 27,012.25
  5. Step 5: Solve for x
    x = 27,012.25/138.40
  6. Step 6: Final answer
    x = 195.18

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.