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Finding the Fourth Proportional to 139.40, 209.16 and 90.56

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Solution

The fourth proportional to 139.40, 209.16 and 90.56 is: 135.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.40 : 209.16 = 90.56 : x
  2. Step 2: Convert to fraction form
    139.40/209.16 = 90.56/x
  3. Step 3: Cross multiply
    139.40x = 209.16 × 90.56
  4. Step 4: Simplify right side
    139.40x = 18,941.53
  5. Step 5: Solve for x
    x = 18,941.53/139.40
  6. Step 6: Final answer
    x = 135.88

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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.