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Finding the Fourth Proportional to 126.90, 189.93 and 72.78

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Solution

The fourth proportional to 126.90, 189.93 and 72.78 is: 108.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    126.90 : 189.93 = 72.78 : x
  2. Step 2: Convert to fraction form
    126.90/189.93 = 72.78/x
  3. Step 3: Cross multiply
    126.90x = 189.93 × 72.78
  4. Step 4: Simplify right side
    126.90x = 13,823.11
  5. Step 5: Solve for x
    x = 13,823.11/126.90
  6. Step 6: Final answer
    x = 108.93

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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.