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Finding the Fourth Proportional to 99.90, 138.03 and 86.68

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Solution

The fourth proportional to 99.90, 138.03 and 86.68 is: 119.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.90 : 138.03 = 86.68 : x
  2. Step 2: Convert to fraction form
    99.90/138.03 = 86.68/x
  3. Step 3: Cross multiply
    99.90x = 138.03 × 86.68
  4. Step 4: Simplify right side
    99.90x = 11,964.44
  5. Step 5: Solve for x
    x = 11,964.44/99.90
  6. Step 6: Final answer
    x = 119.76

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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.