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Finding the Fourth Proportional to 91.67, 126.68 and 78.61

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Solution

The fourth proportional to 91.67, 126.68 and 78.61 is: 108.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.67 : 126.68 = 78.61 : x
  2. Step 2: Convert to fraction form
    91.67/126.68 = 78.61/x
  3. Step 3: Cross multiply
    91.67x = 126.68 × 78.61
  4. Step 4: Simplify right side
    91.67x = 9,958.31
  5. Step 5: Solve for x
    x = 9,958.31/91.67
  6. Step 6: Final answer
    x = 108.63

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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.