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Finding the Fourth Proportional to 91.20, 137.36 and 86.88

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Solution

The fourth proportional to 91.20, 137.36 and 86.88 is: 130.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 137.36 = 86.88 : x
  2. Step 2: Convert to fraction form
    91.20/137.36 = 86.88/x
  3. Step 3: Cross multiply
    91.20x = 137.36 × 86.88
  4. Step 4: Simplify right side
    91.20x = 11,933.84
  5. Step 5: Solve for x
    x = 11,933.84/91.20
  6. Step 6: Final answer
    x = 130.85

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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.