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Finding the Fourth Proportional to 85.35, 128.03 and 66.15

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Solution

The fourth proportional to 85.35, 128.03 and 66.15 is: 99.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.35 : 128.03 = 66.15 : x
  2. Step 2: Convert to fraction form
    85.35/128.03 = 66.15/x
  3. Step 3: Cross multiply
    85.35x = 128.03 × 66.15
  4. Step 4: Simplify right side
    85.35x = 8,468.85
  5. Step 5: Solve for x
    x = 8,468.85/85.35
  6. Step 6: Final answer
    x = 99.23

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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.