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Finding the Fourth Proportional to 91.36, 136.43 and 86.68

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Solution

The fourth proportional to 91.36, 136.43 and 86.68 is: 129.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.36 : 136.43 = 86.68 : x
  2. Step 2: Convert to fraction form
    91.36/136.43 = 86.68/x
  3. Step 3: Cross multiply
    91.36x = 136.43 × 86.68
  4. Step 4: Simplify right side
    91.36x = 11,825.75
  5. Step 5: Solve for x
    x = 11,825.75/91.36
  6. Step 6: Final answer
    x = 129.44

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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.