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Finding the Fourth Proportional to 821.67, 1,230.09 and 639.23

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Solution

The fourth proportional to 821.67, 1,230.09 and 639.23 is: 956.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.67 : 1,230.09 = 639.23 : x
  2. Step 2: Convert to fraction form
    821.67/1,230.09 = 639.23/x
  3. Step 3: Cross multiply
    821.67x = 1,230.09 × 639.23
  4. Step 4: Simplify right side
    821.67x = 786,304.28
  5. Step 5: Solve for x
    x = 786,304.28/821.67
  6. Step 6: Final answer
    x = 956.96

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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.