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Finding the Fourth Proportional to 126.64, 189.86 and 81

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Solution

The fourth proportional to 126.64, 189.86 and 81 is: 121.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.64 : 189.86 = 81 : x
  2. Step 2: Convert to fraction form
    126.64/189.86 = 81/x
  3. Step 3: Cross multiply
    126.64x = 189.86 × 81
  4. Step 4: Simplify right side
    126.64x = 15,378.66
  5. Step 5: Solve for x
    x = 15,378.66/126.64
  6. Step 6: Final answer
    x = 121.44

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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.