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Finding the Fourth Proportional to 172.76, 238.25 and 128.70

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Solution

The fourth proportional to 172.76, 238.25 and 128.70 is: 177.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.76 : 238.25 = 128.70 : x
  2. Step 2: Convert to fraction form
    172.76/238.25 = 128.70/x
  3. Step 3: Cross multiply
    172.76x = 238.25 × 128.70
  4. Step 4: Simplify right side
    172.76x = 30,662.13
  5. Step 5: Solve for x
    x = 30,662.13/172.76
  6. Step 6: Final answer
    x = 177.49

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.