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Finding the Fourth Proportional to 311.31, 428.91 and 261.33

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Solution

The fourth proportional to 311.31, 428.91 and 261.33 is: 360.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.31 : 428.91 = 261.33 : x
  2. Step 2: Convert to fraction form
    311.31/428.91 = 261.33/x
  3. Step 3: Cross multiply
    311.31x = 428.91 × 261.33
  4. Step 4: Simplify right side
    311.31x = 112,087.05
  5. Step 5: Solve for x
    x = 112,087.05/311.31
  6. Step 6: Final answer
    x = 360.05

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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.