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Finding the Fourth Proportional to 85.85, 128.79 and 28.08

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Solution

The fourth proportional to 85.85, 128.79 and 28.08 is: 42.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.85 : 128.79 = 28.08 : x
  2. Step 2: Convert to fraction form
    85.85/128.79 = 28.08/x
  3. Step 3: Cross multiply
    85.85x = 128.79 × 28.08
  4. Step 4: Simplify right side
    85.85x = 3,616.42
  5. Step 5: Solve for x
    x = 3,616.42/85.85
  6. Step 6: Final answer
    x = 42.13

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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.