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Finding the Fourth Proportional to 100.87, 138.78 and 87.01

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Solution

The fourth proportional to 100.87, 138.78 and 87.01 is: 119.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.87 : 138.78 = 87.01 : x
  2. Step 2: Convert to fraction form
    100.87/138.78 = 87.01/x
  3. Step 3: Cross multiply
    100.87x = 138.78 × 87.01
  4. Step 4: Simplify right side
    100.87x = 12,074.90
  5. Step 5: Solve for x
    x = 12,074.90/100.87
  6. Step 6: Final answer
    x = 119.71

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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.