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Finding the Fourth Proportional to 105.78, 146.04 and 91.20

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Solution

The fourth proportional to 105.78, 146.04 and 91.20 is: 125.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.78 : 146.04 = 91.20 : x
  2. Step 2: Convert to fraction form
    105.78/146.04 = 91.20/x
  3. Step 3: Cross multiply
    105.78x = 146.04 × 91.20
  4. Step 4: Simplify right side
    105.78x = 13,318.85
  5. Step 5: Solve for x
    x = 13,318.85/105.78
  6. Step 6: Final answer
    x = 125.91

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.