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Finding the Fourth Proportional to 153.98, 231.38 and 81.90

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Solution

The fourth proportional to 153.98, 231.38 and 81.90 is: 123.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.98 : 231.38 = 81.90 : x
  2. Step 2: Convert to fraction form
    153.98/231.38 = 81.90/x
  3. Step 3: Cross multiply
    153.98x = 231.38 × 81.90
  4. Step 4: Simplify right side
    153.98x = 18,950.02
  5. Step 5: Solve for x
    x = 18,950.02/153.98
  6. Step 6: Final answer
    x = 123.07

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.