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Finding the Fourth Proportional to 126.68, 189.95 and 81

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Solution

The fourth proportional to 126.68, 189.95 and 81 is: 121.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.68 : 189.95 = 81 : x
  2. Step 2: Convert to fraction form
    126.68/189.95 = 81/x
  3. Step 3: Cross multiply
    126.68x = 189.95 × 81
  4. Step 4: Simplify right side
    126.68x = 15,385.95
  5. Step 5: Solve for x
    x = 15,385.95/126.68
  6. Step 6: Final answer
    x = 121.46

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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.