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Finding the Fourth Proportional to 428.26, 642.34 and 208.82

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Solution

The fourth proportional to 428.26, 642.34 and 208.82 is: 313.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.26 : 642.34 = 208.82 : x
  2. Step 2: Convert to fraction form
    428.26/642.34 = 208.82/x
  3. Step 3: Cross multiply
    428.26x = 642.34 × 208.82
  4. Step 4: Simplify right side
    428.26x = 134,133.44
  5. Step 5: Solve for x
    x = 134,133.44/428.26
  6. Step 6: Final answer
    x = 313.21

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.