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Finding the Fourth Proportional to 823.31, 1,235.99 and 638.78

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Solution

The fourth proportional to 823.31, 1,235.99 and 638.78 is: 958.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.31 : 1,235.99 = 638.78 : x
  2. Step 2: Convert to fraction form
    823.31/1,235.99 = 638.78/x
  3. Step 3: Cross multiply
    823.31x = 1,235.99 × 638.78
  4. Step 4: Simplify right side
    823.31x = 789,516.32
  5. Step 5: Solve for x
    x = 789,516.32/823.31
  6. Step 6: Final answer
    x = 958.96

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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.