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Finding the Fourth Proportional to 89.76, 134.68 and 85.43

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Solution

The fourth proportional to 89.76, 134.68 and 85.43 is: 128.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.76 : 134.68 = 85.43 : x
  2. Step 2: Convert to fraction form
    89.76/134.68 = 85.43/x
  3. Step 3: Cross multiply
    89.76x = 134.68 × 85.43
  4. Step 4: Simplify right side
    89.76x = 11,505.26
  5. Step 5: Solve for x
    x = 11,505.26/89.76
  6. Step 6: Final answer
    x = 128.18

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.