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Finding the Fourth Proportional to 136.40, 188.20 and 81.12

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Solution

The fourth proportional to 136.40, 188.20 and 81.12 is: 111.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.40 : 188.20 = 81.12 : x
  2. Step 2: Convert to fraction form
    136.40/188.20 = 81.12/x
  3. Step 3: Cross multiply
    136.40x = 188.20 × 81.12
  4. Step 4: Simplify right side
    136.40x = 15,267.59
  5. Step 5: Solve for x
    x = 15,267.59/136.40
  6. Step 6: Final answer
    x = 111.94

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.