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Finding the Fourth Proportional to 91.78, 137.32 and 74.64

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Solution

The fourth proportional to 91.78, 137.32 and 74.64 is: 111.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.78 : 137.32 = 74.64 : x
  2. Step 2: Convert to fraction form
    91.78/137.32 = 74.64/x
  3. Step 3: Cross multiply
    91.78x = 137.32 × 74.64
  4. Step 4: Simplify right side
    91.78x = 10,249.56
  5. Step 5: Solve for x
    x = 10,249.56/91.78
  6. Step 6: Final answer
    x = 111.68

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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.