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Finding the Fourth Proportional to 642.12, 963.12 and 209.28

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Solution

The fourth proportional to 642.12, 963.12 and 209.28 is: 313.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.12 : 963.12 = 209.28 : x
  2. Step 2: Convert to fraction form
    642.12/963.12 = 209.28/x
  3. Step 3: Cross multiply
    642.12x = 963.12 × 209.28
  4. Step 4: Simplify right side
    642.12x = 201,561.75
  5. Step 5: Solve for x
    x = 201,561.75/642.12
  6. Step 6: Final answer
    x = 313.90

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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.