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Finding the Fourth Proportional to 99.50, 137.21 and 66.78

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Solution

The fourth proportional to 99.50, 137.21 and 66.78 is: 92.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.50 : 137.21 = 66.78 : x
  2. Step 2: Convert to fraction form
    99.50/137.21 = 66.78/x
  3. Step 3: Cross multiply
    99.50x = 137.21 × 66.78
  4. Step 4: Simplify right side
    99.50x = 9,162.55
  5. Step 5: Solve for x
    x = 9,162.55/99.50
  6. Step 6: Final answer
    x = 92.09

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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.