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Finding the Fourth Proportional to 89.42, 123.92 and 87.80

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Solution

The fourth proportional to 89.42, 123.92 and 87.80 is: 121.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.42 : 123.92 = 87.80 : x
  2. Step 2: Convert to fraction form
    89.42/123.92 = 87.80/x
  3. Step 3: Cross multiply
    89.42x = 123.92 × 87.80
  4. Step 4: Simplify right side
    89.42x = 10,879.78
  5. Step 5: Solve for x
    x = 10,879.78/89.42
  6. Step 6: Final answer
    x = 121.68

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.