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Finding the Fourth Proportional to 312.45, 431.21 and 238.64

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Solution

The fourth proportional to 312.45, 431.21 and 238.64 is: 329.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.45 : 431.21 = 238.64 : x
  2. Step 2: Convert to fraction form
    312.45/431.21 = 238.64/x
  3. Step 3: Cross multiply
    312.45x = 431.21 × 238.64
  4. Step 4: Simplify right side
    312.45x = 102,902.76
  5. Step 5: Solve for x
    x = 102,902.76/312.45
  6. Step 6: Final answer
    x = 329.34

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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.