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Finding the Fourth Proportional to 831.21, 1,247.09 and 398.13

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Solution

The fourth proportional to 831.21, 1,247.09 and 398.13 is: 597.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.21 : 1,247.09 = 398.13 : x
  2. Step 2: Convert to fraction form
    831.21/1,247.09 = 398.13/x
  3. Step 3: Cross multiply
    831.21x = 1,247.09 × 398.13
  4. Step 4: Simplify right side
    831.21x = 496,501.95
  5. Step 5: Solve for x
    x = 496,501.95/831.21
  6. Step 6: Final answer
    x = 597.32

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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.