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Finding the Fourth Proportional to 645.88, 891.40 and 397.21

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Solution

The fourth proportional to 645.88, 891.40 and 397.21 is: 548.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.88 : 891.40 = 397.21 : x
  2. Step 2: Convert to fraction form
    645.88/891.40 = 397.21/x
  3. Step 3: Cross multiply
    645.88x = 891.40 × 397.21
  4. Step 4: Simplify right side
    645.88x = 354,072.99
  5. Step 5: Solve for x
    x = 354,072.99/645.88
  6. Step 6: Final answer
    x = 548.20

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.