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Finding the Fourth Proportional to 172.28, 258.37 and 85.57

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Solution

The fourth proportional to 172.28, 258.37 and 85.57 is: 128.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.28 : 258.37 = 85.57 : x
  2. Step 2: Convert to fraction form
    172.28/258.37 = 85.57/x
  3. Step 3: Cross multiply
    172.28x = 258.37 × 85.57
  4. Step 4: Simplify right side
    172.28x = 22,107.86
  5. Step 5: Solve for x
    x = 22,107.86/172.28
  6. Step 6: Final answer
    x = 128.32

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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.