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Finding the Fourth Proportional to 139.07, 208.31 and 90.20

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Solution

The fourth proportional to 139.07, 208.31 and 90.20 is: 135.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.07 : 208.31 = 90.20 : x
  2. Step 2: Convert to fraction form
    139.07/208.31 = 90.20/x
  3. Step 3: Cross multiply
    139.07x = 208.31 × 90.20
  4. Step 4: Simplify right side
    139.07x = 18,788.07
  5. Step 5: Solve for x
    x = 18,788.07/139.07
  6. Step 6: Final answer
    x = 135.10

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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.