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Finding the Fourth Proportional to 91.20, 125.72 and 86.98

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Solution

The fourth proportional to 91.20, 125.72 and 86.98 is: 119.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 125.72 = 86.98 : x
  2. Step 2: Convert to fraction form
    91.20/125.72 = 86.98/x
  3. Step 3: Cross multiply
    91.20x = 125.72 × 86.98
  4. Step 4: Simplify right side
    91.20x = 10,935.13
  5. Step 5: Solve for x
    x = 10,935.13/91.20
  6. Step 6: Final answer
    x = 119.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.