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Finding the Fourth Proportional to 428.76, 643.18 and 197.60

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Solution

The fourth proportional to 428.76, 643.18 and 197.60 is: 296.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.76 : 643.18 = 197.60 : x
  2. Step 2: Convert to fraction form
    428.76/643.18 = 197.60/x
  3. Step 3: Cross multiply
    428.76x = 643.18 × 197.60
  4. Step 4: Simplify right side
    428.76x = 127,092.37
  5. Step 5: Solve for x
    x = 127,092.37/428.76
  6. Step 6: Final answer
    x = 296.42

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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.