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Finding the Fourth Proportional to 91.90, 138.37 and 81.14

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Solution

The fourth proportional to 91.90, 138.37 and 81.14 is: 122.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.90 : 138.37 = 81.14 : x
  2. Step 2: Convert to fraction form
    91.90/138.37 = 81.14/x
  3. Step 3: Cross multiply
    91.90x = 138.37 × 81.14
  4. Step 4: Simplify right side
    91.90x = 11,226.24
  5. Step 5: Solve for x
    x = 11,226.24/91.90
  6. Step 6: Final answer
    x = 122.16

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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.