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Finding the Fourth Proportional to 312.40, 431.56 and 289.36

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Solution

The fourth proportional to 312.40, 431.56 and 289.36 is: 399.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.40 : 431.56 = 289.36 : x
  2. Step 2: Convert to fraction form
    312.40/431.56 = 289.36/x
  3. Step 3: Cross multiply
    312.40x = 431.56 × 289.36
  4. Step 4: Simplify right side
    312.40x = 124,876.20
  5. Step 5: Solve for x
    x = 124,876.20/312.40
  6. Step 6: Final answer
    x = 399.73

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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.