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Finding the Fourth Proportional to 642.70, 964.05 and 209.90

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Solution

The fourth proportional to 642.70, 964.05 and 209.90 is: 314.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.70 : 964.05 = 209.90 : x
  2. Step 2: Convert to fraction form
    642.70/964.05 = 209.90/x
  3. Step 3: Cross multiply
    642.70x = 964.05 × 209.90
  4. Step 4: Simplify right side
    642.70x = 202,354.10
  5. Step 5: Solve for x
    x = 202,354.10/642.70
  6. Step 6: Final answer
    x = 314.85

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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.