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Finding the Fourth Proportional to 138.93, 208.21 and 66.63

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Solution

The fourth proportional to 138.93, 208.21 and 66.63 is: 99.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.93 : 208.21 = 66.63 : x
  2. Step 2: Convert to fraction form
    138.93/208.21 = 66.63/x
  3. Step 3: Cross multiply
    138.93x = 208.21 × 66.63
  4. Step 4: Simplify right side
    138.93x = 13,873.03
  5. Step 5: Solve for x
    x = 13,873.03/138.93
  6. Step 6: Final answer
    x = 99.86

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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.