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Finding the Fourth Proportional to 126.31, 189.43 and 85.57

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Solution

The fourth proportional to 126.31, 189.43 and 85.57 is: 128.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.31 : 189.43 = 85.57 : x
  2. Step 2: Convert to fraction form
    126.31/189.43 = 85.57/x
  3. Step 3: Cross multiply
    126.31x = 189.43 × 85.57
  4. Step 4: Simplify right side
    126.31x = 16,209.53
  5. Step 5: Solve for x
    x = 16,209.53/126.31
  6. Step 6: Final answer
    x = 128.33

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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.