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Finding the Fourth Proportional to 91.61, 136.49 and 85.72

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Solution

The fourth proportional to 91.61, 136.49 and 85.72 is: 127.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.61 : 136.49 = 85.72 : x
  2. Step 2: Convert to fraction form
    91.61/136.49 = 85.72/x
  3. Step 3: Cross multiply
    91.61x = 136.49 × 85.72
  4. Step 4: Simplify right side
    91.61x = 11,699.92
  5. Step 5: Solve for x
    x = 11,699.92/91.61
  6. Step 6: Final answer
    x = 127.71

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.