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Finding the Fourth Proportional to 90.39, 136.07 and 85.14

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Solution

The fourth proportional to 90.39, 136.07 and 85.14 is: 128.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.39 : 136.07 = 85.14 : x
  2. Step 2: Convert to fraction form
    90.39/136.07 = 85.14/x
  3. Step 3: Cross multiply
    90.39x = 136.07 × 85.14
  4. Step 4: Simplify right side
    90.39x = 11,584.57
  5. Step 5: Solve for x
    x = 11,584.57/90.39
  6. Step 6: Final answer
    x = 128.16

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.