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Finding the Fourth Proportional to 90.69, 125.16 and 66.21

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Solution

The fourth proportional to 90.69, 125.16 and 66.21 is: 91.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.69 : 125.16 = 66.21 : x
  2. Step 2: Convert to fraction form
    90.69/125.16 = 66.21/x
  3. Step 3: Cross multiply
    90.69x = 125.16 × 66.21
  4. Step 4: Simplify right side
    90.69x = 8,286.84
  5. Step 5: Solve for x
    x = 8,286.84/90.69
  6. Step 6: Final answer
    x = 91.38

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.