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Finding the Fourth Proportional to 138.84, 208.50 and 66.78

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Solution

The fourth proportional to 138.84, 208.50 and 66.78 is: 100.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.84 : 208.50 = 66.78 : x
  2. Step 2: Convert to fraction form
    138.84/208.50 = 66.78/x
  3. Step 3: Cross multiply
    138.84x = 208.50 × 66.78
  4. Step 4: Simplify right side
    138.84x = 13,923.63
  5. Step 5: Solve for x
    x = 13,923.63/138.84
  6. Step 6: Final answer
    x = 100.29

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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.