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Finding the Fourth Proportional to 428.23, 642.21 and 208.86

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Solution

The fourth proportional to 428.23, 642.21 and 208.86 is: 313.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.23 : 642.21 = 208.86 : x
  2. Step 2: Convert to fraction form
    428.23/642.21 = 208.86/x
  3. Step 3: Cross multiply
    428.23x = 642.21 × 208.86
  4. Step 4: Simplify right side
    428.23x = 134,131.98
  5. Step 5: Solve for x
    x = 134,131.98/428.23
  6. Step 6: Final answer
    x = 313.22

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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.