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Finding the Fourth Proportional to 645.98, 891.20 and 397.15

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Solution

The fourth proportional to 645.98, 891.20 and 397.15 is: 547.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.98 : 891.20 = 397.15 : x
  2. Step 2: Convert to fraction form
    645.98/891.20 = 397.15/x
  3. Step 3: Cross multiply
    645.98x = 891.20 × 397.15
  4. Step 4: Simplify right side
    645.98x = 353,943.86
  5. Step 5: Solve for x
    x = 353,943.86/645.98
  6. Step 6: Final answer
    x = 547.92

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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.