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Finding the Fourth Proportional to 85.54, 128.08 and 76.98

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Solution

The fourth proportional to 85.54, 128.08 and 76.98 is: 115.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.54 : 128.08 = 76.98 : x
  2. Step 2: Convert to fraction form
    85.54/128.08 = 76.98/x
  3. Step 3: Cross multiply
    85.54x = 128.08 × 76.98
  4. Step 4: Simplify right side
    85.54x = 9,859.60
  5. Step 5: Solve for x
    x = 9,859.60/85.54
  6. Step 6: Final answer
    x = 115.26

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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.