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Finding the Fourth Proportional to 89.21, 123.15 and 65.85

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Solution

The fourth proportional to 89.21, 123.15 and 65.85 is: 90.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.21 : 123.15 = 65.85 : x
  2. Step 2: Convert to fraction form
    89.21/123.15 = 65.85/x
  3. Step 3: Cross multiply
    89.21x = 123.15 × 65.85
  4. Step 4: Simplify right side
    89.21x = 8,109.43
  5. Step 5: Solve for x
    x = 8,109.43/89.21
  6. Step 6: Final answer
    x = 90.90

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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.