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Finding the Fourth Proportional to 85.62, 127.91 and 78.78

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Solution

The fourth proportional to 85.62, 127.91 and 78.78 is: 117.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.62 : 127.91 = 78.78 : x
  2. Step 2: Convert to fraction form
    85.62/127.91 = 78.78/x
  3. Step 3: Cross multiply
    85.62x = 127.91 × 78.78
  4. Step 4: Simplify right side
    85.62x = 10,076.36
  5. Step 5: Solve for x
    x = 10,076.36/85.62
  6. Step 6: Final answer
    x = 117.69

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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.