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Finding the Fourth Proportional to 85.25, 117.78 and 78.68

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Solution

The fourth proportional to 85.25, 117.78 and 78.68 is: 108.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.25 : 117.78 = 78.68 : x
  2. Step 2: Convert to fraction form
    85.25/117.78 = 78.68/x
  3. Step 3: Cross multiply
    85.25x = 117.78 × 78.68
  4. Step 4: Simplify right side
    85.25x = 9,266.93
  5. Step 5: Solve for x
    x = 9,266.93/85.25
  6. Step 6: Final answer
    x = 108.70

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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.