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Finding the Fourth Proportional to 426.40, 639.68 and 221.08

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Solution

The fourth proportional to 426.40, 639.68 and 221.08 is: 331.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.40 : 639.68 = 221.08 : x
  2. Step 2: Convert to fraction form
    426.40/639.68 = 221.08/x
  3. Step 3: Cross multiply
    426.40x = 639.68 × 221.08
  4. Step 4: Simplify right side
    426.40x = 141,420.45
  5. Step 5: Solve for x
    x = 141,420.45/426.40
  6. Step 6: Final answer
    x = 331.66

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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.