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Finding the Fourth Proportional to 428.55, 642.30 and 197.20

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Solution

The fourth proportional to 428.55, 642.30 and 197.20 is: 295.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.55 : 642.30 = 197.20 : x
  2. Step 2: Convert to fraction form
    428.55/642.30 = 197.20/x
  3. Step 3: Cross multiply
    428.55x = 642.30 × 197.20
  4. Step 4: Simplify right side
    428.55x = 126,661.56
  5. Step 5: Solve for x
    x = 126,661.56/428.55
  6. Step 6: Final answer
    x = 295.56

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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.