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Finding the Fourth Proportional to 136.49, 188.40 and 81.21

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Solution

The fourth proportional to 136.49, 188.40 and 81.21 is: 112.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    136.49 : 188.40 = 81.21 : x
  2. Step 2: Convert to fraction form
    136.49/188.40 = 81.21/x
  3. Step 3: Cross multiply
    136.49x = 188.40 × 81.21
  4. Step 4: Simplify right side
    136.49x = 15,299.96
  5. Step 5: Solve for x
    x = 15,299.96/136.49
  6. Step 6: Final answer
    x = 112.10

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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.