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Finding the Fourth Proportional to 312.45, 431.72 and 257.14

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Solution

The fourth proportional to 312.45, 431.72 and 257.14 is: 355.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.45 : 431.72 = 257.14 : x
  2. Step 2: Convert to fraction form
    312.45/431.72 = 257.14/x
  3. Step 3: Cross multiply
    312.45x = 431.72 × 257.14
  4. Step 4: Simplify right side
    312.45x = 111,012.48
  5. Step 5: Solve for x
    x = 111,012.48/312.45
  6. Step 6: Final answer
    x = 355.30

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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.