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Finding the Fourth Proportional to 91.90, 138.02 and 69

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Solution

The fourth proportional to 91.90, 138.02 and 69 is: 103.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.90 : 138.02 = 69 : x
  2. Step 2: Convert to fraction form
    91.90/138.02 = 69/x
  3. Step 3: Cross multiply
    91.90x = 138.02 × 69
  4. Step 4: Simplify right side
    91.90x = 9,523.38
  5. Step 5: Solve for x
    x = 9,523.38/91.90
  6. Step 6: Final answer
    x = 103.63

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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.