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Finding the Fourth Proportional to 123.87, 170.89 and 81.90

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Solution

The fourth proportional to 123.87, 170.89 and 81.90 is: 112.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.87 : 170.89 = 81.90 : x
  2. Step 2: Convert to fraction form
    123.87/170.89 = 81.90/x
  3. Step 3: Cross multiply
    123.87x = 170.89 × 81.90
  4. Step 4: Simplify right side
    123.87x = 13,995.69
  5. Step 5: Solve for x
    x = 13,995.69/123.87
  6. Step 6: Final answer
    x = 112.99

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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.