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Finding the Fourth Proportional to 89.78, 123.04 and 86.70

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Solution

The fourth proportional to 89.78, 123.04 and 86.70 is: 118.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.78 : 123.04 = 86.70 : x
  2. Step 2: Convert to fraction form
    89.78/123.04 = 86.70/x
  3. Step 3: Cross multiply
    89.78x = 123.04 × 86.70
  4. Step 4: Simplify right side
    89.78x = 10,667.57
  5. Step 5: Solve for x
    x = 10,667.57/89.78
  6. Step 6: Final answer
    x = 118.82

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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.