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Finding the Fourth Proportional to 91.79, 137.71 and 81.71

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Solution

The fourth proportional to 91.79, 137.71 and 81.71 is: 122.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.79 : 137.71 = 81.71 : x
  2. Step 2: Convert to fraction form
    91.79/137.71 = 81.71/x
  3. Step 3: Cross multiply
    91.79x = 137.71 × 81.71
  4. Step 4: Simplify right side
    91.79x = 11,252.42
  5. Step 5: Solve for x
    x = 11,252.42/91.79
  6. Step 6: Final answer
    x = 122.59

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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.