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Finding the Fourth Proportional to 138.21, 190.68 and 89.08

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Solution

The fourth proportional to 138.21, 190.68 and 89.08 is: 122.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.21 : 190.68 = 89.08 : x
  2. Step 2: Convert to fraction form
    138.21/190.68 = 89.08/x
  3. Step 3: Cross multiply
    138.21x = 190.68 × 89.08
  4. Step 4: Simplify right side
    138.21x = 16,986.82
  5. Step 5: Solve for x
    x = 16,986.82/138.21
  6. Step 6: Final answer
    x = 122.90

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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.