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Finding the Fourth Proportional to 89.71, 133.66 and 85.78

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Solution

The fourth proportional to 89.71, 133.66 and 85.78 is: 127.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.71 : 133.66 = 85.78 : x
  2. Step 2: Convert to fraction form
    89.71/133.66 = 85.78/x
  3. Step 3: Cross multiply
    89.71x = 133.66 × 85.78
  4. Step 4: Simplify right side
    89.71x = 11,464.88
  5. Step 5: Solve for x
    x = 11,464.88/89.71
  6. Step 6: Final answer
    x = 127.80

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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.