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Finding the Fourth Proportional to 126.48, 189.78 and 72.42

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Solution

The fourth proportional to 126.48, 189.78 and 72.42 is: 108.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.48 : 189.78 = 72.42 : x
  2. Step 2: Convert to fraction form
    126.48/189.78 = 72.42/x
  3. Step 3: Cross multiply
    126.48x = 189.78 × 72.42
  4. Step 4: Simplify right side
    126.48x = 13,743.87
  5. Step 5: Solve for x
    x = 13,743.87/126.48
  6. Step 6: Final answer
    x = 108.66

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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.