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Finding the Fourth Proportional to 69.78, 96.31 and 40.28

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Solution

The fourth proportional to 69.78, 96.31 and 40.28 is: 55.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    69.78 : 96.31 = 40.28 : x
  2. Step 2: Convert to fraction form
    69.78/96.31 = 40.28/x
  3. Step 3: Cross multiply
    69.78x = 96.31 × 40.28
  4. Step 4: Simplify right side
    69.78x = 3,879.25
  5. Step 5: Solve for x
    x = 3,879.25/69.78
  6. Step 6: Final answer
    x = 55.59

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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.