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Finding the Fourth Proportional to 426.78, 639.19 and 221.53

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Solution

The fourth proportional to 426.78, 639.19 and 221.53 is: 331.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.78 : 639.19 = 221.53 : x
  2. Step 2: Convert to fraction form
    426.78/639.19 = 221.53/x
  3. Step 3: Cross multiply
    426.78x = 639.19 × 221.53
  4. Step 4: Simplify right side
    426.78x = 141,599.76
  5. Step 5: Solve for x
    x = 141,599.76/426.78
  6. Step 6: Final answer
    x = 331.79

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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.