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Finding the Fourth Proportional to 139.90, 209.91 and 91.06

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Solution

The fourth proportional to 139.90, 209.91 and 91.06 is: 136.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.90 : 209.91 = 91.06 : x
  2. Step 2: Convert to fraction form
    139.90/209.91 = 91.06/x
  3. Step 3: Cross multiply
    139.90x = 209.91 × 91.06
  4. Step 4: Simplify right side
    139.90x = 19,114.40
  5. Step 5: Solve for x
    x = 19,114.40/139.90
  6. Step 6: Final answer
    x = 136.63

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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.