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Finding the Fourth Proportional to 107.20, 160.68 and 85.78

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Solution

The fourth proportional to 107.20, 160.68 and 85.78 is: 128.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    107.20 : 160.68 = 85.78 : x
  2. Step 2: Convert to fraction form
    107.20/160.68 = 85.78/x
  3. Step 3: Cross multiply
    107.20x = 160.68 × 85.78
  4. Step 4: Simplify right side
    107.20x = 13,783.13
  5. Step 5: Solve for x
    x = 13,783.13/107.20
  6. Step 6: Final answer
    x = 128.57

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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.