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Finding the Fourth Proportional to 831.89, 1,247.97 and 399.05

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Solution

The fourth proportional to 831.89, 1,247.97 and 399.05 is: 598.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.89 : 1,247.97 = 399.05 : x
  2. Step 2: Convert to fraction form
    831.89/1,247.97 = 399.05/x
  3. Step 3: Cross multiply
    831.89x = 1,247.97 × 399.05
  4. Step 4: Simplify right side
    831.89x = 498,002.43
  5. Step 5: Solve for x
    x = 498,002.43/831.89
  6. Step 6: Final answer
    x = 598.64

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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.