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Finding the Fourth Proportional to 89.65, 122.87 and 86.91

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Solution

The fourth proportional to 89.65, 122.87 and 86.91 is: 119.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.65 : 122.87 = 86.91 : x
  2. Step 2: Convert to fraction form
    89.65/122.87 = 86.91/x
  3. Step 3: Cross multiply
    89.65x = 122.87 × 86.91
  4. Step 4: Simplify right side
    89.65x = 10,678.63
  5. Step 5: Solve for x
    x = 10,678.63/89.65
  6. Step 6: Final answer
    x = 119.11

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.