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Finding the Fourth Proportional to 136.80, 205.20 and 91.17

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Solution

The fourth proportional to 136.80, 205.20 and 91.17 is: 136.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.80 : 205.20 = 91.17 : x
  2. Step 2: Convert to fraction form
    136.80/205.20 = 91.17/x
  3. Step 3: Cross multiply
    136.80x = 205.20 × 91.17
  4. Step 4: Simplify right side
    136.80x = 18,708.08
  5. Step 5: Solve for x
    x = 18,708.08/136.80
  6. Step 6: Final answer
    x = 136.76

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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.