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Finding the Fourth Proportional to 91.62, 136.80 and 81.36

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Solution

The fourth proportional to 91.62, 136.80 and 81.36 is: 121.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.62 : 136.80 = 81.36 : x
  2. Step 2: Convert to fraction form
    91.62/136.80 = 81.36/x
  3. Step 3: Cross multiply
    91.62x = 136.80 × 81.36
  4. Step 4: Simplify right side
    91.62x = 11,130.05
  5. Step 5: Solve for x
    x = 11,130.05/91.62
  6. Step 6: Final answer
    x = 121.48

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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.