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Finding the Fourth Proportional to 99.65, 149.28 and 81.39

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Solution

The fourth proportional to 99.65, 149.28 and 81.39 is: 121.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.65 : 149.28 = 81.39 : x
  2. Step 2: Convert to fraction form
    99.65/149.28 = 81.39/x
  3. Step 3: Cross multiply
    99.65x = 149.28 × 81.39
  4. Step 4: Simplify right side
    99.65x = 12,149.31
  5. Step 5: Solve for x
    x = 12,149.31/99.65
  6. Step 6: Final answer
    x = 121.92

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.