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Finding the Fourth Proportional to 138.78, 208.32 and 113.40

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Solution

The fourth proportional to 138.78, 208.32 and 113.40 is: 170.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 208.32 = 113.40 : x
  2. Step 2: Convert to fraction form
    138.78/208.32 = 113.40/x
  3. Step 3: Cross multiply
    138.78x = 208.32 × 113.40
  4. Step 4: Simplify right side
    138.78x = 23,623.49
  5. Step 5: Solve for x
    x = 23,623.49/138.78
  6. Step 6: Final answer
    x = 170.22

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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.