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Finding the Fourth Proportional to 642.20, 963.30 and 398.80

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Solution

The fourth proportional to 642.20, 963.30 and 398.80 is: 598.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.20 : 963.30 = 398.80 : x
  2. Step 2: Convert to fraction form
    642.20/963.30 = 398.80/x
  3. Step 3: Cross multiply
    642.20x = 963.30 × 398.80
  4. Step 4: Simplify right side
    642.20x = 384,164.04
  5. Step 5: Solve for x
    x = 384,164.04/642.20
  6. Step 6: Final answer
    x = 598.20

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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.