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Finding the Fourth Proportional to 311.80, 431.35 and 256.43

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Solution

The fourth proportional to 311.80, 431.35 and 256.43 is: 354.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.80 : 431.35 = 256.43 : x
  2. Step 2: Convert to fraction form
    311.80/431.35 = 256.43/x
  3. Step 3: Cross multiply
    311.80x = 431.35 × 256.43
  4. Step 4: Simplify right side
    311.80x = 110,611.08
  5. Step 5: Solve for x
    x = 110,611.08/311.80
  6. Step 6: Final answer
    x = 354.75

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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.