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Finding the Fourth Proportional to 89.67, 133.64 and 86.78

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Solution

The fourth proportional to 89.67, 133.64 and 86.78 is: 129.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.67 : 133.64 = 86.78 : x
  2. Step 2: Convert to fraction form
    89.67/133.64 = 86.78/x
  3. Step 3: Cross multiply
    89.67x = 133.64 × 86.78
  4. Step 4: Simplify right side
    89.67x = 11,596.18
  5. Step 5: Solve for x
    x = 11,596.18/89.67
  6. Step 6: Final answer
    x = 129.32

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.