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Finding the Fourth Proportional to 172.19, 258.11 and 85.47

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Solution

The fourth proportional to 172.19, 258.11 and 85.47 is: 128.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.19 : 258.11 = 85.47 : x
  2. Step 2: Convert to fraction form
    172.19/258.11 = 85.47/x
  3. Step 3: Cross multiply
    172.19x = 258.11 × 85.47
  4. Step 4: Simplify right side
    172.19x = 22,060.66
  5. Step 5: Solve for x
    x = 22,060.66/172.19
  6. Step 6: Final answer
    x = 128.12

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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.