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Finding the Fourth Proportional to 85.20, 117.84 and 83.76

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Solution

The fourth proportional to 85.20, 117.84 and 83.76 is: 115.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.20 : 117.84 = 83.76 : x
  2. Step 2: Convert to fraction form
    85.20/117.84 = 83.76/x
  3. Step 3: Cross multiply
    85.20x = 117.84 × 83.76
  4. Step 4: Simplify right side
    85.20x = 9,870.28
  5. Step 5: Solve for x
    x = 9,870.28/85.20
  6. Step 6: Final answer
    x = 115.85

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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.