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Finding the Fourth Proportional to 139.38, 208.99 and 66.21

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Solution

The fourth proportional to 139.38, 208.99 and 66.21 is: 99.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.38 : 208.99 = 66.21 : x
  2. Step 2: Convert to fraction form
    139.38/208.99 = 66.21/x
  3. Step 3: Cross multiply
    139.38x = 208.99 × 66.21
  4. Step 4: Simplify right side
    139.38x = 13,837.23
  5. Step 5: Solve for x
    x = 13,837.23/139.38
  6. Step 6: Final answer
    x = 99.28

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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.