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Finding the Fourth Proportional to 85.46, 117.86 and 78.09

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Solution

The fourth proportional to 85.46, 117.86 and 78.09 is: 107.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.46 : 117.86 = 78.09 : x
  2. Step 2: Convert to fraction form
    85.46/117.86 = 78.09/x
  3. Step 3: Cross multiply
    85.46x = 117.86 × 78.09
  4. Step 4: Simplify right side
    85.46x = 9,203.30
  5. Step 5: Solve for x
    x = 9,203.30/85.46
  6. Step 6: Final answer
    x = 107.70

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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.