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Finding the Fourth Proportional to 91.88, 138.32 and 71.72

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Solution

The fourth proportional to 91.88, 138.32 and 71.72 is: 107.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.88 : 138.32 = 71.72 : x
  2. Step 2: Convert to fraction form
    91.88/138.32 = 71.72/x
  3. Step 3: Cross multiply
    91.88x = 138.32 × 71.72
  4. Step 4: Simplify right side
    91.88x = 9,920.31
  5. Step 5: Solve for x
    x = 9,920.31/91.88
  6. Step 6: Final answer
    x = 107.97

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.