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Finding the Fourth Proportional to 831.86, 1,245.39 and 639.86

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Solution

The fourth proportional to 831.86, 1,245.39 and 639.86 is: 957.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.86 : 1,245.39 = 639.86 : x
  2. Step 2: Convert to fraction form
    831.86/1,245.39 = 639.86/x
  3. Step 3: Cross multiply
    831.86x = 1,245.39 × 639.86
  4. Step 4: Simplify right side
    831.86x = 796,875.25
  5. Step 5: Solve for x
    x = 796,875.25/831.86
  6. Step 6: Final answer
    x = 957.94

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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.