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Finding the Fourth Proportional to 312.90, 431.70 and 239.10

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Solution

The fourth proportional to 312.90, 431.70 and 239.10 is: 329.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.90 : 431.70 = 239.10 : x
  2. Step 2: Convert to fraction form
    312.90/431.70 = 239.10/x
  3. Step 3: Cross multiply
    312.90x = 431.70 × 239.10
  4. Step 4: Simplify right side
    312.90x = 103,219.47
  5. Step 5: Solve for x
    x = 103,219.47/312.90
  6. Step 6: Final answer
    x = 329.88

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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.