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Finding the Fourth Proportional to 428.86, 643.45 and 197.86

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Solution

The fourth proportional to 428.86, 643.45 and 197.86 is: 296.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.86 : 643.45 = 197.86 : x
  2. Step 2: Convert to fraction form
    428.86/643.45 = 197.86/x
  3. Step 3: Cross multiply
    428.86x = 643.45 × 197.86
  4. Step 4: Simplify right side
    428.86x = 127,313.02
  5. Step 5: Solve for x
    x = 127,313.02/428.86
  6. Step 6: Final answer
    x = 296.86

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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.