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Finding the Fourth Proportional to 91.38, 136.78 and 66.94

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Solution

The fourth proportional to 91.38, 136.78 and 66.94 is: 100.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.38 : 136.78 = 66.94 : x
  2. Step 2: Convert to fraction form
    91.38/136.78 = 66.94/x
  3. Step 3: Cross multiply
    91.38x = 136.78 × 66.94
  4. Step 4: Simplify right side
    91.38x = 9,156.05
  5. Step 5: Solve for x
    x = 9,156.05/91.38
  6. Step 6: Final answer
    x = 100.20

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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.