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Finding the Fourth Proportional to 100.85, 138.82 and 87.89

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Solution

The fourth proportional to 100.85, 138.82 and 87.89 is: 120.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.85 : 138.82 = 87.89 : x
  2. Step 2: Convert to fraction form
    100.85/138.82 = 87.89/x
  3. Step 3: Cross multiply
    100.85x = 138.82 × 87.89
  4. Step 4: Simplify right side
    100.85x = 12,199.76
  5. Step 5: Solve for x
    x = 12,199.76/100.85
  6. Step 6: Final answer
    x = 120.98

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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.