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Finding the Fourth Proportional to 645.98, 891.30 and 397.20

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Solution

The fourth proportional to 645.98, 891.30 and 397.20 is: 548.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.98 : 891.30 = 397.20 : x
  2. Step 2: Convert to fraction form
    645.98/891.30 = 397.20/x
  3. Step 3: Cross multiply
    645.98x = 891.30 × 397.20
  4. Step 4: Simplify right side
    645.98x = 354,029.19
  5. Step 5: Solve for x
    x = 354,029.19/645.98
  6. Step 6: Final answer
    x = 548.05

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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.