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Finding the Fourth Proportional to 85.52, 128.10 and 77.87

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Solution

The fourth proportional to 85.52, 128.10 and 77.87 is: 116.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.52 : 128.10 = 77.87 : x
  2. Step 2: Convert to fraction form
    85.52/128.10 = 77.87/x
  3. Step 3: Cross multiply
    85.52x = 128.10 × 77.87
  4. Step 4: Simplify right side
    85.52x = 9,975.15
  5. Step 5: Solve for x
    x = 9,975.15/85.52
  6. Step 6: Final answer
    x = 116.64

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.