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Finding the Fourth Proportional to 69.78, 104.05 and 64.91

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Solution

The fourth proportional to 69.78, 104.05 and 64.91 is: 96.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    69.78 : 104.05 = 64.91 : x
  2. Step 2: Convert to fraction form
    69.78/104.05 = 64.91/x
  3. Step 3: Cross multiply
    69.78x = 104.05 × 64.91
  4. Step 4: Simplify right side
    69.78x = 6,754.14
  5. Step 5: Solve for x
    x = 6,754.14/69.78
  6. Step 6: Final answer
    x = 96.79

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.