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Finding the Fourth Proportional to 312.45, 431.30 and 279.65

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Solution

The fourth proportional to 312.45, 431.30 and 279.65 is: 386.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    312.45 : 431.30 = 279.65 : x
  2. Step 2: Convert to fraction form
    312.45/431.30 = 279.65/x
  3. Step 3: Cross multiply
    312.45x = 431.30 × 279.65
  4. Step 4: Simplify right side
    312.45x = 120,611.59
  5. Step 5: Solve for x
    x = 120,611.59/312.45
  6. Step 6: Final answer
    x = 386.02

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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.